Louse Flies? Are You "Ked"-ing Me?

Until recently, insect diversity here along the Front Range of Colorado this spring has been suppressed by cool, wet weather. How amazing, then, that I should see not one, but two specimens of an insect I had seen only once or twice in all my years. I am speaking of "louse flies" in the family Hippoboscidae.

Back at the end of December in 2009, I volunteered to do a guest blog for my good friend Dave Small after he sent me an e-mail inquiring whether I might know the identity of an insect in an image he attached with his message. I didn’t quite understand the story at first, like why two hunters were involved, and why the insect was adhered to hard candy. The image was clear enough, though, that I could tell what the creature was, and that this was not a tall tale evolved from heavy drinking. Here is the rest of that piece.

Deer and related animals play host to a variety of parasitic invertebrates, including the familiar, slow-moving ticks. Such blood-feeding creatures are quick to abandon a deceased host, however, and so animals harvested during the hunt often yield some strange, living cargo during inspection and dressing.

The specimen discovered by these two hunters is an insect known as a “louse fly,” among the most peculiar of insect parasites. They are much more nimble than ticks, dodging attempts to catch them as they skirt through a host’s fur. Their flattened shape, top to bottom, and talon-like claws enhance their ability to slip between hairs and grip the hide of the host, avoiding licking and biting efforts to dislodge them.

Members of the fly family Hippoboscidae, most known louse flies are actually parasites of birds. The most infamous member of the family, though, is the “sheep ked,” well-known to those who manage flocks of ovine livestock. The adult flies are wingless, but they find each other easily for mating when the host animals crowd together.

Back to the specimen the hunters found, and collected by sticking it with a piece of hard candy. That would probably be a “deer ked,” Lipoptena cervi. Here is a terrific image of a related species, Lipoptena depressa from northern California. Both species have a life history that is typical of the entire family of louse flies, but truly mind-blowing compared to other insects.

Female louse flies do not lay eggs. They grow one offspring at a time, within their bodies, much like mammals. A single larva develops inside the equivalent of a uterus, feeding from a “milk” gland. When mature, it is “born alive,” dropping to the ground where it immediately buries itself and pupates. An adult fly emerges weeks later. Deer ked are winged, at least initially, but females that have found a host will break off their wings, the better to maneuver through the dense, coarse hair of their host.

Wingless deer ked after two days in captivity

While keds are known to transmit certain diseases from host to host, they are for the most part not economically important. Consequently, little is known about them. Kudos to our hunter friends for bringing this one into the spotlight.

The first specimen I found this year landed on my while I was hiking in Aiken Canyon Preserve off of highway 115, about fifteen miles northeast of Penrose, Colorado on Memorial Day (May 30). I recognized it fast enough to grab it while it was tangled up in some of my sparse arm hair.

After chilling the tiny, 3 millimeter creature in the fridge for a few minutes, I dumped it out into a casserole dish to photograph it. Well, it was apparently completely unaffected by the cold and flew off after I fired off only a couple of legible shots. About 30-45 seconds later, from out of nowhere, it landed on my chest. I guess it pays to be a mammal to keep these flies under some degree of control. A couple of days later, I found the fly had self-broken its wings, such that they were mere stubs. Despite that, the insect was still highly mobile and most of my shots were as blurry as when it had flight capability.

The next encounter was at a blacklight set up to attract moths in Cheyenne Mountain State Park on the night of June 4. I routinely scrutinize the most minute of creatures in the event they may be of interest, and much to my surprise there was another "ked." It, too, was fully winged but, perhaps mesmerized by the ultraviolet light, sat motionless and allowed me to take multiple images....most of which are still not optimal because the blame bug is so miniscule.

Want to find your own louse flies? You might volunteer to go hunting game mammals and birds with your friends to get a chance at shaking one loose. Otherwise, good luck. These insects are common, but so seldom stray from hosts that it is sheer serendipity to stumble across one. More than likely, the fly will find you.

Two Spiny-butts

There is no way around it. The most apt description of most tachinid flies is "spiny-butt." The abdomen of a good many members of the family Tachinidae is covered in long, obvious spines. Why? I haven't found an explanation, but that physical characteristic helps one to immediately recognize these flies as something other than a house fly, blow fly, flesh fly, or other similar dipteran. That said, two large tachinid flies are frequently confused with each other: Adejeania and Paradejeania.

Adejeania vexatrix

Here in western North America, these two animals are commonly observed as they take nectar from late summer and fall wildflowers. I, for one, can never remember which one is which. Ok, so one of them has beak-like mouthparts, is slightly smaller than the other, a bit brighter in color, and declines in abundance toward autumn....

Ah, it is Adejeania vexatrix that has these characters! The "beak" is somewhat unusual in the Tachinidae, and it is the elongated palps that form a sheath around the remainder of the mouthparts. This species ranges from British Columbia and Alberta south through California, Arizona, and New Mexico. Adult flies are on the wing in July and August, but in the more southerly reaches of their distribution can be found in September or even October.

It is known that this fly is a parasite of caterpillars, but the exact host species has yet to be documented. When a caterpillar yields an organism other than the adult moth or butterfly, it can be a real challenge to identify what kind of Lepidoptera it was *supposed* to metamorphose into.

Macromya crocata strongly resembles A. vexatrix, is found in similar forested habitats, but lacks the "beak" of its look-alike. The same information applies to Hystricia abrupta, another common species frequently mistaken for A. vexatrix.

Paradejeania rutilioides is even more robust, and spinier, than the species just discussed. It tends to be a more subdued orange in color, and the adult insect is found most often in August, September, and October (though stragglers can be out in November or even December). Here in Colorado I find this species commonly on flowers of rabbitbrush (Chrysothamnus or Ericameria depending on the botanical authority you consult).

Paradejeania rutilioides

This species goes by the common name of "Spiny Tachinid Fly" or "Hedgehog Fly," the latter epithet coined by fly expert and author Stephen A. Marshall. It has a similar distribution as A. vexatrix, divided geographically into two subspecies, one northern and one southern. The fly is a known parasite of caterpillars of Edwards' Glassy-wing, Hemihyalea edwardsii, a tiger moth in the family Erebidae (subfamily Arctiidae).

Tachinid flies in general are remarkable creatures that are of enormous benefit to us through their parasitic lifestyle. We would surely be overrun with pest caterpillars, stink bugs, and other insects were it not for the ability of tachinids to control pest populations. Further, they are important flower visitors that complement pollinators like bees.

Sources: Arnaud, Paul H., Jr. 1978. A Host-Parasite Catalog of North American Tachinidae (Diptera). Washington, DC: United States Department of Agriculture Miscellaneous Publication No. 1319. 860 pp.
O'Hara, James E. 2012. "Review of Tachinid Fly Diversity in the Gila National Forest, New Mexico," The New Mexico Botanist Special Issue No. 3: 32-41.
O'Hara, James. E. 2013. "Tachinidae Resources," North American Dipterists Society.
Young, Chen, et al. 2005. "Species Paradejeania rutilioides - Spiny Tachinid Fly," Bugguide.net.

A Bed Bug Primer

”Sleep tight, don’t let the bed bugs bite.” That rhyme had no relevance for decades, but not any longer. After vanishing from the scene after World War II, bed bugs are back in our nightmares and, more importantly, our reality. Thankfully, bed bugs pose no threat from the transmission of blood-borne pathogens, but what they lack in virulence is more than made up for in litigations. Here is what you need to know about these insidious pests.

What is a Bed Bug?

Cimex lectularius is a member of the family Cimicidae in the order of true bugs (Hemiptera). Like all true bugs they have piercing-sucking mouthparts. Bed bugs use their beaks to drink the blood of human beings. Yes, we are the preferred host of this parasitic insect. Pets, other mammals, and birds suffice in a pinch for starving bed bugs, but people are the real target.

These are small, wingless insects, dorso-ventrally flattened (top to bottom) to the point of being paper thin. Adults measure only 4-6 millimeters, 7-8 millimeters immediately after feeding. First instar nymphs (those just emerged from the egg) are only one millimeter, and so pale as to be nearly invisible on the typical mattress or sheet.

First instar bed bug nymphLife Cycle

Bed bugs go through five instars before becoming adults. An instar is the interval between molts. Each bed bug must have one blood meal in order to graduate from one instar to the next.

Bed bugs of various instars

Eggs usually hatch 6-10 days after being laid, though it can take up to 21 days. Each nymph stage lasts about one week under ideal conditions, longer if blood meals are irregular. Adult bed bugs typically live ten months to a year, feeding about every ten days. Since the average female can lay 500 eggs in her lifetime, you can imagine how quickly a population of bed bugs can build.

Second or third instar nymphDo I Have Bed Bugs?

Obviously, inexplicable bite wounds can be a clue that you might have bed bugs. Bites are typically in a linear arrangement of three, evidenced as red, slightly-raised welts. However, some people do not react at all to bites, while others experience worse symptoms. If your bedmate complains, take them seriously.

A fair-sized population of bed bugs gives off a sweet, distinctive odor, so use your sense of smell. The French word for bed bug is punaise, a reference to this stinky aspect of bed bug biology.

If you suspect bed bugs, strip the bed and look for the insects and their signs, especially along mattress seams, under mattress buttons, the slots where the bed frame attaches to headboard and footboard, and other tight spaces. Bed bugs have to poop, and reddish or dark brownish stains are another sign of their presence.

Avoiding Bed Bugs

Inspect, inspect, inspect! You cannot be too careful in avoiding infestations. When traveling, inspect your lodging thoroughly, and elevate your luggage off the floor. Maybe put the suitcase in the bathtub. Look behind headboards that are flush against the wall. Take drawers out of the nightstand and examine them carefully. Look under carpet where it goes up the wall like a baseboard. Look in mattress seams and under mattress buttons.

Any place where there is serial occupancy is prone to infestations, from five star hotels to rental cabins, dorms, prisons, hospitals, movie theaters, planes, trains, buses, taxicabs….

Beware of secondhand furniture and avoid used mattresses. The rise in popularity of thrift stores is credited in part with expanding the bed bug empire, so again, inspect items thoroughly before purchasing.

Treating for Bed Bugs

Don’t panic, but do seek professional help. Bed bugs are extremely difficult to eradicate, so find a reputable, recommended company that has a successful track record. Understand that the extermination process is highly invasive. Furniture will have to be taken apart, perhaps even discarded. Your best bet may be heat treatment. Unfortunately, this is usually the most expensive option, but it is highly effective.

Complications may arise if you are in a multi-family dwelling, rental, or are the proprietor of a hotel, motel, campground, or other lodging enterprise. This is when legal representation is often sought to determine (or avoid) liability. Do make sure your interests are protected, but try to refrain from making any situation more adversarial than it already is.

Sources: Berenbaum, May R. 1989. Ninety-nine Gnats, Nits, and Nibblers. Urbana: University of Illinois Press. 263 pp.
Centers for Disease Control and Prevention. 2013. Parasites – Bed Bugs
Maestre, Ralph H. 2011. The Bed Bug Book. NY: Skyhorse Publishing. 181 pp.
National Institutes of Health. 2014. “Bedbugs,” Medline Plus.

Ibaliid Wasps

I am constantly surprised. I am also fortunate to have an extra set of keen eyes whenever my wife and I go exploring together. The evening of June 9 we decided to enjoy Sinton Pond Open Space here in Colorado Springs. While trying to get a picture of a damselfly, Heidi spied something even more interesting: a sleeping wasp in the family Ibaliidae.

I know, I’d never heard of them, either, at least until I found a specimen in Cincinnati when I lived there. I tried to turn it into some kind of ichneumon wasp, but it simply didn’t fit any of the characters for Ichneumonidae. I don’t recall how I finally found the answer, but I was certainly shocked to learn its nearest relatives are gall wasps.

There is one genus, Ibalia, in North America, with six species, the most widespread of which appears to be Ibalia anceps. Its distribution extends from Nova Scotia, Ontario, and Wisconsin south to Florida and Texas and west to Colorado. Geographic variation accounts for different color patterns in the wings. Ibalia anceps adults fly mostly in late May and early June.

Ibalia are parasites of horntail woodwasps in the family Siricidae. The female wasp lays an egg on the horntail grub, which is inside a dead, dying, or weakened deciduous tree, such as hickory. The larva that hatches from the ibaliid egg then penetrates the cuticle of the horntail larva and begins feeding as an internal parasite. Later, as the larva grows, it exits the host and finishes feeding as an external parasite.

Here locally, the only common horntail is the Pigeon Tremex, Tremex columba, so that must be the host. Indeed, elsewhere across its range, I. anceps is associated most often with T. columba. Please see my post on the Pigeon Tremex for more information about that wasp.

Ibaliids may be recognized by the laterally compressed abdomen. The abdomen is so thin that it conveys the impression that the rear end of the insect was smashed between the pages of a heavy book. Male Ibalia have fifteen segments in each antenna, while females have only thirteen segments. Females also possess an ovipositor (egg-laying organ). Specimens average about 12-14 mm in length, which is gigantic compared to their tiny relatives in the superfamily Cynipoidea, most of which are around three millimeters.

Keep your eyes open for these unique wasps. Take images if you are able, and share them with other naturalists and entomologists.

Sources: Goulet, Henri and John T. Huber (eds.) 1993. Hymenoptera of the World: An identification guide to families. Ottawa: Agriculture Canada. 668 pp.
Nendick-Mason, Hannah, et al. 2006. “Species Ibalia anceps,” Bugguide.net.
Smith, David R. and Nathan M. Schiff. 2002. “A review of the siricid woodwasps and their ibaliid parasitoids (Hymenoptera: Siricidae, Ibaliidae) in the eastern United States, with emphasis on the mid-Atlantic region,” Proc. Entomol. Soc. Wash. 104(1): 174-194.

Wasp vs. Wasp

My wife and I went down to Fountain Creek Regional Park in Fountain, Colorado recently (the evening of June 2, 2013), and I happened upon an interesting scene. About five or six female mason wasps, Symmorphus sp., were nesting in beetle borings in a cottonwood log by the side of the trail. About four cuckoo wasps, Chrysis sp., were hanging out around the holes the wasps were using as nests. Heidi said I must have spent 45 minutes taking pictures of them all, but it was worth it because I got to observe what was happening.

The above image is one of only two really nice shots I got of the female Symmorphus mason wasps. They would alight near their nest hole, and dive in very quickly. If I approached too quickly with the camera, the wasp would fly off before entering. If I waited too long, I would get a shot of the wasp’s abdomen disappearing, or a seemingly empty hole. Waiting for the wasp to emerge was basically futile, as she would exit much more quickly than was possible to focus.

You have to have an appreciation of the size of the players and the beetle borings to know what I was up against. The borings are probably the exit holes of deathwatch beetles, family Anobiidae, which bore in dead, solid wood as larvae. The diameter of each hole is about the same as the end of a retracted ballpoint pen (about 3 millimeters). Yes, both the mason wasps and cuckoo wasps could fit through those holes.

”Science has strict rules against anthropomorphism, but if you ask me, those chrysidids were cunning and calculating.”

Meanwhile, the bright metallic green cuckoo wasps were not as easily disturbed as the mason wasps. They might run randomly around between holes, but most of the time they sat quietly in the vicinity of a group of holes. Science has strict rules against anthropomorphism, but if you ask me, those chrysidids were cunning and calculating. They were waiting for the wasps to show them which holes were active nests worthy of their attention.

Cuckoo wasps are parasitic in the nests of other solitary wasps. They can’t sting, but the last few segments of the abdomen of the female telescopes into an egg-laying organ that can reach into the bottom of one of those nest tunnels. The cuckoo wasp lays an egg in the nest of its host, and the larva that hatches generally consumes the meal intended for the host offspring.

In the case of Symmorphus, females catch and paralyze leaf beetle larvae that are free-living, or are leaf-miners (living between the layers of a leaf). At least one species of Symmorphus attacks leaf-mining moth caterpillars on occasion. The larval victims are packed into a cell along the length of the beetle boring, and the mother wasp lays her own egg on the last victim. She then creates a partition of mud or chewed wood fibers, and begins a new cell. The process is repeated such that several cells usually occupy one tunnel.

The mason wasps, for their part, were also quite cognizant of the cuckoo wasps. I witnessed at least one altercation whereby a female mason wasp fended off a too-eager chrysidid at the entrance to her nest. Cuckoo wasps, while they can’t sting, have a dense, pitted exoskeleton that effectively repels the bites and stings of their hosts. They can even roll into a ball as a last resort, becoming virtually impregnable.

Without collecting specimens of the wasps, which I did not do, I cannot conclude the species I was observing. Process of elimination narrows the possibilities to Symmorphus cristatus or S. canadensis for the mason wasps. The cuckoo wasps could represent one or more species in the Chrysis coerulans species group. Scientists are still trying to sort out how many species there actually are in that complex.

After getting up from my baseball catcher’s stance, I could feel how my legs had stiffened. The pain was worth the gain, though, and I encourage my readers to endure for the sake of personal and collective knowledge. Field observations are not the scientific priority they once were in the fledgling years of ethology (study of animal behavior). It could easily be you who makes history with a new host record for a predator or parasite, or records some other hitherto unknown association between species.

Sources: Bohart, R.M. and Lynn S. Kimsey. 1982. “A Synopsis of the Chrysididae in America North of Mexico,” Mem. Am. Entomol. Inst. 33: 1-266
Buck, M. Marshall, S.A., and Cheung, D.K.B. 2008. “Identification Atlas of the Vespidae (Hymenoptera: Aculeata) of the Northeastern Nearctic Region,” Canadian Journal of Arthropod Identification No. 5: 492 pp.
Krombein, Karl V. 1967. Trap-nesting Wasps and Bees: Life Histories, Nests, and Associates. Washington, DC: Smithsonian Press. 570 pp.

Wasp Wednesday: Orussid Wasps

I do not select stories for this blog based on maximum weirdness, they just turn out that way. Take for example the strange case of wasps in the family Orussidae. For starters, they are not often seen in the forests they inhabit; and they are easily mistaken for carpenter ants at first glance.

There are only 75 species known, in sixteen genera, for the entire world. Nine species, in four genera, occur in North America north of Mexico.

What makes these wasps truly unique is their history of defying proper classification within the order Hymenoptera. Let us start with the fact that evidence points to a parasitic lifestyle in the larval stage. Ok, so they must be related to Braconidae and Ichneumonidae. Nope. Anatomical features of adult orussids are much more similar to horntails and sawflies. No way! Way! At one point, two scientists tried to solve the dilemma by erecting an entirely new suborder, the Idiogastra, just for the Orussidae. Until recently, many entomologists lumped the Orussidae as an aberrant family within the suborder Symphyta, making them the most advanced of that group, and the most primitive of parasitic wasps.

Today, the family is placed in its own superfamily, Orussoidea, in the suborder Apocrita, the umbrella group for all parasitic and parasitoid Hymenoptera (Vilhelmsen, 2003).

Adult orussids are most often found on logs and dead, standing trees in those sections where the bark has been stripped off. Solid, but sun-bleached wood seems to be favored, and the female wasps crawl and dart across the surface in search of the tunnels of wood-boring insects. Each female detects a larval host through “vibrational sounding,” much like a bat hunts moths at night. She taps her antennae on the surface of the wood, and apparently receives the reverberating “echoes” through a subgenual organ inside each front tibia (the “shin” joint of the leg) (Broad & Quicke, 2000). Indeed, the tips of her antennae are thickened and club-like; and the tips of the front tibiae have thin cuticle concealing the vibrational receptors.

It is assumed that orussids are general parasitoids on various wood-boring insects including horntails, longhorned beetles, and jewel beetles. Most confirmed records in North America have been for jewel beetles (family Buprestidae). The female wasp usually accesses the host grub by backing into an exit hole from which another host beetle had already emerged. She may reach a grub with her ovipositor, which while coiled within her thoracic and abdominal cavities, can be more than twice the length of her body (Vilhemsen, et al., 2001).

The larva that hatches from the extremely long, slender egg is probably not entirely immobile, being equipped with a row of backward-curving spines on all dorsal thoracid and abdominal segments. The spines probably help it inch its way down tunnels to reach a host. Once it finds a host grub, the orussid larva attaches itself as an external parasite.

© Scott Justis via Bugguide.net

Look for adult orussids in both coniferous and deciduous forests, especially along the edges of meadows or where there are other sunny openings in the canopy. The wasps not only pace rapidly back and forth over a log, changing direction abruptly, but they can also jump.

Our four species in the genus Orussus are the ones you are most likely to see, if you don’t assume they are ants. Dark bands on the otherwise clear wings help disguise them as carpenter ants when the wings are folded over their back. Note the very globular head, with antennae inserted just above the mouth. There are teeth or tubercles on the top of the head.

© M J Hatfield via Bugguide.net

Our understanding of these insects, their geographic distribution, and behavior, are still sparse, so your observations can be key. Take a look at these images by Stephen Hart and these by Rollin Coville for inspiration.

Sources: Broad, Gavin R. and Donald L.J. Quicke. 2000. “The adaptive significance of host location by vibrational sounding in parasitoid wasps,” Proc. R. Soc. London B 267(1460): 2403-2409.
Goulet, Henri and John T. Huber, eds. 1993. Hymenoptera of the World: An identification guide to families. Ottawa: Agriculture Canada. 668 pp.
Powell, J.A. and W.J. Turner. 1975. “Observations on Oviposition Behavior and Host Selection in Orussus occidentalis (Hymenoptera: Siricoidea),” J. Kans. Ent. Soc. 48(3): 299-307.
Vilhelmsen, Lars. 2003. “Phylogeny and classification of the Orussidae (Insecta, Hymenoptera), a basal parasitic wasp taxon,” Zool. J. Linnean Soc. 139: 337-418.
Vilhelmsen, Lars, Nunzio Isidoro, Roberto Romani, Hasan H. Basibuyuk, and Donald L.J. Quicke. 2001. “Host location and oviposition in a basal group of parasitic wasps: the subgenual organ, ovipositor apparatus and associated structures in the Orussidae (Hymenoptera, Insecta),” Zoomorphology 121(2): 63-84.

Wasp Wednesday: Pseudomalus auratus

At this time of year, we decorate the inside of our homes with festive ornaments, many of them green or gold or red. Nature offers her own ornamental organisms, but many are too small to grab our attention unless we look closely. Such is the case for the brilliant little cuckoo wasp, Pseudomalus auratus.

Cuckoo wasps in general are also known as “jewel wasps,” so colorful are they. This particular little gem averages only four millimeters in length, so despite its contrasting colors of emerald (head and thorax) and ruby red (abdomen), Pseudomalus auratus is easily overlooked. Rarely does this wasp visit flowers, either, so you have to seek it out elsewhere.

This species is not native to North America, but is common throughout Europe, Asia, and northern Africa. It was likely introduced here accidentally prior to 1828. Until fairly recently, records in the U.S. were limited to the Atlantic seaboard, but now it may turn up almost anywhere.

Larvae of this wasp are kleptoparasites in the nests of other solitary wasps, and solitary bees, that nest inside hollow twigs, pre-existing cavities in wood, and similar situations. Known hosts include the smaller wasps in the family Crabronidae, and bees in the genera Ceratina (small carpenter bees, family Apidae), Hylaeus (masked bees, family Colletidae), and Anthidium (wool-carder or cotton bees, family Megachilidae). The cuckoo wasp grub feeds on the provisions stored by the mother of the host larva. They literally steal the meal provided by the host for its offspring.

Pseudomalus auratus is not without its own enemies. Parasitic wasps in the families Ichneumonidae and Torymidae are known to kill the larvae, though those casualties might be the result of the parasites attacking the same host as the cuckoo wasp.

Look for adults of the cuckoo wasp around aphid colonies and extrafloral nectaries on various plants. I found specimens in Ohio at aphid colonies on Honeyvine Milkweed (Ampelamus albidus) and Northern Catalpa (Catalpa speciosa). The specimen shown here is from Colorado Springs, found sipping on the tacky exudates of Common Sunflower (Helianthus annuus).

Please share your own observations of this species with the scientific community. Our understanding of the distribution and hosts for Pseudomalus auratus in North America is in its infancy.

Sources: Agnoli G.L. & Rosa P., 2012 : Pseudomalus auratus (Linnaeus, 1758) . In: Chrysis.net Database of the Italian Chrysididae, interim version 12 December 2012.
Species page at Discoverlife.org.
Species page on Encyclopedia of Life.
Bohart, R.M. and Lynn S. Kimsey. 1982. “A Synopsis of the Chrysididae in America North of Mexico,” Mem. Am. Entomol. Inst. 33: 1-266 (Note: species is listed as Omalus auratus).

Wasp Wednesday: Carrot Wasps

Around the holidays, we humans tend to pack on the pounds as we indulge in feasts and parties at Thanksgiving and Christmas. Wasps do not have this problem. One family of wasps in particular manages to stay super-slim and slender: the Gasteruptiidae or “carrot wasps.”

There are at least fifteen species of carrot wasps in North America, all in the genus Gasteruption. Five of those occur in the eastern U.S. and Canada. At first glance, they might be mistaken for ichneumon wasps, or even sphecid wasps in the genus Ammophila. This is probably not coincidental, since carrot wasps do not sting, but could benefit by looking like other wasps that can sting.

You can easily identify carrot wasps by the following characters:

• Pronounced “neck” between head and thorax.
• Abdomen attached high up on the thorax, not between hind legs.
• Hind tibiae swollen (think “leg warmers”).
• Antennae with 13 segments (male) or 14 segments (female). Ichneumon wasps have far more antennal segments.
• Ovipositor sometimes with a white tip

Species identification often hinges on the texture of various parts of the thorax; and to a lesser degree on color pattern.

These are not terribly large insects, from 13-40 millimeters depending on the species, and much of that length owing to the long ovipositor in females. They are so skinny they remind one of a flying needle.

The adult wasps are most often encountered at flowers, especially those umbelliferous blooms in the parsley family, hence their common name of “carrot wasps.” I have also seen them at White Sweet Clover (Melilotus alba) and Desert Broom (Baccharis sarothroides), and Leafy Spurge (Euphorbia esula). Flight activity seems to peak in late spring (latter half of May) and/or mid-summer (July).

male

The biology of gasteruptiids is rather poorly known, but so far our North American species appear to be parasites of solitary bees and wasps that nest in twigs or borings in wood. The female wasp needs her long ovipositor to reach the depths of a host’s tunnel and deposit an egg. The larval carrot wasp that hatches usually feeds on the pollen, nectar, or prey stored as food for the host larva, rather than the host larva itself.

Trap-nesting for solitary bees and wasps could easily reveal many more host records for Gasteruption wasps, if one keeps careful notes.

Sources: Jennings, John T. and Andrew R. Deans. 2006. “Gasteruptiidae,” The Tree of Life Web Project, Version 22.
Smith, David R. 1996. “Review of the Gasteruptiidae (Hymenoptera) of Eastern North America,” Proc. Entomol. Soc. Wash. 98(3): 491-499.
Townes, Henry. 1950. “The Nearctic Species of Gasteruptiidae (Hymenoptera),” Proc. U.S. Nat. Mus. 100(3259): 85-145 (Note that this reference includes what is now the family Aulacidae).

Wasp Wednesday: Blue-winged Wasp

One of the most common solitary wasps of late summer and fall is a member of the family Scoliidae known as the “Blue-winged Wasp,” Scolia dubia. This is a fairly large insect, 20-25 millimeters in length, and easily identified by its bi-colored abdomen: Black on the upper half and red on the bottom half, with two bright yellow spots in the red area. There is rarely any variation in that color scheme, either. The common name stems from the brilliant blue highlights in the black wings that shine when sunlight hits them just right.

Scolia dubia is also a widespread species, found from Massachusetts to Florida, and west to Colorado, Arizona, and southern California. I have found them in New Jersey, Ohio, and Colorado. They are parasites of the grubs of scarab beetles, particularly the Green June Beetle, Cotinis nitida, and Japanese Beetles, Popilla japonica. Since Colorado has neither of these species, the Blue-winged Wasp must exploit a different host here. We certainly have plenty of May beetles (genus Phyllophaga), and the Bumble Flower Beetle (Euphoria inda), so I suspect those are the local hosts here in Colorado Springs.

The female wasp somehow divines the presence of beetle grubs underground while flying low over the surface of the soil in what approximates a figure-eight pattern. When she detects one, she lands, and sets about unearthing it. Scoliid wasps have strong legs that are heavily spined. This adaptation facilitates their digging activities.

An exposed scarab grub will writhe around and seek to rebury itself immediately. The wasp stings the larva to paralyze it and allow her to manipulate it. She may leave the grub in situ, or tunnel below it, excavating a small chamber where she deposits the beetle larva and lays an egg on it, perpendicular its body. She then seals the chamber and leaves to start the process all over again, often staying underground and digging her way to the next grub.

Interestingly, these wasps may sting several grubs without laying eggs on them. The paralysis of the beetle larva is usually permanent, so regardless of whether they become food for larval wasps, the beetle grubs are unable to complete their own life cycle. This is a good thing if you happen to have an infestation of “white grubs” in your lawn or garden.

Back to the egg on the beetle grub, though. The wasp larva that hatches feeds as an external parasite on the grub for one or two weeks before spinning a silken cocoon around itself. There it will remain as a pre-pupa for the winter, pupating the following summer and eventually emerging as an adult wasp.

Male and female scoliid wasps commonly visit flowers to feed on nectar (and perhaps pollen). I find them most often on White Sweet Clover, Melilotus alba, thoroughworts (genus Eupatorium), and goldenrod (Solidago spp.). Males can be identified by their long antennae and overall more slender appearance. Males have a distinctive, three-pronged “pseudostinger” that is part of their external genitalia. Males cannot sting, and females are loathe to sting unless physically molested.

Another interesting aspect of the males is their behavior. Males also fly near the ground in a sinuous pattern, hoping to detect virgin females emerging from the ground. This usually happens in the morning, and males abandon their searching by late afternoon. At that time, they may gather together to roost for the night on vegetation, as the image below depicts.

© Tim Moyer via Bugguide.net

Keep an eye out for the Blue-winged Wasp in your own yard. Remember they are beneficial, but beware that large numbers of them may indicate you have a serious problem with white grubs.

Sources: Grissell, Edward E. 2007. “Scoliid Wasps of Florida, Campsomeris, Scolia, and Trielis spp. (Insecta: Hymenoptera: Scoliidae),” Featured Creatures, document EENY-409, Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences (IFAS), University of Florida.
Rau, Phil and Nellie. 1918. Wasp Studies Afield. Princeton, NJ: Princeton University Press. 372 pp (Dover Edition).

Wasp Wednesday: Dasymutilla bioculata

Last Sunday I wrote about a brightly-colored jumping spider, Phidippus apacheanus, and suggested that it was probably a mimic of wingless female wasps called velvet ants. Today I would like to introduce you to one of those wasps. Velvet ants comprise the family Mutillidae, and can be found across most of the North American continent. They are most common in arid habitats like deserts and prairies. Here in Colorado Springs, Dasymutilla bioculata is one of the most frequently encountered species.

Many velvet ants are bright orange, red, or yellow, and black. This pattern advertises the fact that females can sting. So powerful is that sting that one of the larger species is called the “cow killer.” Folklore has it that the pain is enough to kill livestock. It is no mystery why less well-defended insects, or spiders, would want to look like velvet ants. No sensible predator wants to mess with them.

I have seen female Dasymutilla bioculata scurrying over sandy paths in open fields, usually on overcast days or around dusk when the air temperature begins to cool slightly. Both genders like to clamber around on the stems and leaves of Common Sunflower, Helianthus annuus. They find the sweet, sticky secretions of the plant to their liking.

Male velvet ants have the customary two pairs of wings and fly well, but they can also be colored very differently from their female counterparts. This has resulted in much confusion, even among experts who seek to associate the males with the appropriate females and vice versa.

Dasymutilla bioculata is an excellent example of “lumping,” whereby scientists decide that several different species are actually variations of just one species. A paper published in 2010 resulted in lumping no fewer than twenty-one former species and subspecies under the name Dasymutilla bioculata. The authors of the publication used molecular analysis to find common nuclear ribosomal RNA markers among all the former species and subspecies. Morphological differences (what you see when you look at the external structure of the insects) were deemed too inconsistent to be the sole determining factors in differentiating species.

No wonder I didn’t recognize these Colorado specimens. George Waldren, a velvet ant expert and volunteer editor at Bugguide.net was kind enough to set me straight, identifying my images of the females. The images of the male shown here may or may not be the same species. You just can’t tell from images alone.

Dasymutilla bioculata ranges across the entire continent, and from southern Canada to Mexico. Adults vary in size from about 8 millimeters to 16 or 17 millimeters in body length. The bigger the specimen, the better it fed as a larva.

The life histories of velvet ants are often as mysterious as their classification, or simply unknown. Those species we do know well are parasitic on other insects, especially other solitary wasps and bees. Female velvet ants scour the ground for signs of their hosts, which often dig burrows in the soil. Velvet ants can even detect closed burrows, digging them open to gain access. Once inside, the female lays an egg in the cell or cells at the end of the underground tunnel. The larval wasp that hatches will attack the pupa of the host, or a larva in diapause (inactive state).

The known hosts for Dasymutilla bioculata are sand wasps in the genera Bembix and Microbembex. Should an adult sand wasp discover a velvet ant invading her nest, she will of course attack it. Velvet ants have an extra-thick exoskeleton that effectively deflects the bites and stings of their enemies.

I would advise anyone searching for velvet ants to avoid picking them up. Do scoop one into a vial some time and put it up to your ear. Do you hear that? Both genders of these wasps can “squeak” by rapidly rubbing their abdominal segments together. Music to my own ears anyway.

Sources: Kits, Joel, et al. 2011. “Species Dasymutilla bioculata,” Bugguide.net.
Krombein, Karl V. and Paul D. Hurd. 1979. Catalog of Hymenoptera in America North of Mexico. Washington, DC: Smithsonian Institution Press. 2188 pp.
Williams, K.A., D.G. Manley, E.M. Pilgrim, C.D. von Dohlen & J.P. Pitts. 2010. “Multifaceted assessment of species validity in the Dasymutilla bioculata species group (Hymenoptera: Mutillidae). Syst Entomol, 36(1): 180-191.

Wasp Wednesday: Perilampid Wasps

Do you remember that old saying that “good things come in small packages?” That is certainly the case with the compact little wasps known as perilampids (family Perilampidae). They range in size from 1.3-5.5 millimeters in length, but oh are they spectacular. Many, if not most, are brilliant metallic green or blue. Some are wholly black in color. They can be easily confused with small cuckoo wasps in the family Chrysididae, and are sometimes found in similar situations, especially around aphid colonies, or the extrafloral nectaries of sunflowers.

My latest encounter with a perilampid was indeed on a sunflower plant, where it was intent on imbibing the sweet excretions from the hairy stem. I recognized it as a perilampid by the short, strongly elbowed antennae, and the abdomen, which in perilampids is shaped more or less like a triangle or an inverted pyramid. Cuckoo wasps have an oval or rounded abdomen without sharp corners.

The beauty of these tiny insects is more than matched by their bizarre lifestyle. They are parasitic in the larval stage, usually on other parasitic insects like the larvae of tachinid flies, or ichneumon wasps or braconid wasps living as parasites inside caterpillars or other insect larvae. This is known as “hyperparasitism,” whereby they are parasites of parasites.

Even stranger is the way the wasps find their hosts. The female perilampid “broadcasts” large numbers of eggs, laying them on leaves, buds, cracks in bark, under lichens, and in other locations where the larvae that hatch might have hope of encountering a host. She may deposit as many as 500 eggs in this manner. A flattened, mobile larva (“planidium” or “planidiform”as scientists call it) hatches from each egg, and attempts to attach itself to any moving object by its mandibles. Obviously, a great many such planidium larvae fail because they glom onto the wrong animal.

Those that are successful in finding the appropriate secondary larval host then penetrate the host’s cuticle. Once inside they begin searching for the primary host, a parasite of the secondary host. They will then enter that larva in the same way. There they wait until this primary host pupates. The perilampid larva then exits, molting into a grub-like larva that feeds as an external parasite. It goes through two or three more instars (the intervals between molts) before pupating itself inside the host cocoon or puparium.

Some perilampids in the subfamily Perilampniae are able to adjust their life cycle in the absence of a primary host, simply feeding as a parasite on the secondary host. Perilampus hyalinus is such an example, able to complete its life cycle as a parasite of certain sawfly larvae (Diprionidae, Tenthredinidae) if no primary host is contained within it. Another species of Perilampus is recorded from immature grasshoppers (Acrididae), gaining access via flesh fly parasites (Sarcophagidae). Still other species in the subfamily are recorded as primary parasites of lacewing larvae (Chrysopidae), wasp larvae (Sphecidae), and beetle larvae (weevils in the Curculionidae).

The life cycles of members of the subfamily Chrysolampinae are less well known, but records indicate beetle larvae (Lycidae, Anobiidae, Nitidulidae) as hosts.

The classification of perilampids has given scientists fits. They are variously set aside as their own family (Perilampidae), or lumped in with the Pteromalidae. Even if ascribed to their own family, those members of the subfamily Chrysolampinae are usually put into the Pteromalidae. I don’t get it either. The number of recognized genera is also up for discussion. Some authorities recognize only fifteen genera in the world, whereas others suggest there may be as many as twice that number (thirty genera). There are 260-277 species currently recognized, with 36 species in North America north of Mexico (in five genera). Many more species await discovery and/or names and descriptions.

Sources: Goulet, Henri and John T. Huber (eds.). 1993. Hymenoptera of the World: An identification guide to families. Ottawa, Ontario: Agriculture Canada. 668 pp.
Pitkin, B.R. 2004. “Perilampidae,” Universal Chalcidoidea Database, Natural History Museum, United Kingdom
Grissell, E. Eric and M. E. Schauff. 2003. “Family Perilampidae,” Systematic Entomology Laboratory, USDA Agrigultural Research Station, Beltsville, Maryland.
Grissell, Eric. 2010. Bees, Wasps, and Ants: The indispensable role of Hymenoptera in gardens. Portland, Oregon: Timber Press. 335 pp.