Wednesday, August 29, 2012

Wasp Wednesday: Ageniella accepta/conflicta

Expert entomologists caution that species-level identifications cannot always be made from images of live specimens in the wild. Such is the case with most spider wasps of the family Pompilidae. It is difficult enough to get any image, unless the wasp is enjoying flower nectar and oblivious to anything else, or digging a burrow and intent on her activities. So, I preface this article by stating that I can’t be certain the species depicted here is Ageniella accepta or A. conflicta.

When I first spotted one of these wasps running around on a sunflower plant here in Colorado Springs, I passed it off as just another kind of ant. Indeed, ants rule the sunflowers, driving off any insects that want to lick the sweet, sticky substance exuded by the plant. Closer inspection revealed that this was no ant. The extra-long legs were one clue. So was the fact that it was winged, but the dark bands across the wings give the impression of the “nodes” that link an ant’s abdomen to its thorax.

Why mimic an ant? Ants are, like wasps, members of the order Hymenoptera. They defend themselves and their nestmates by biting viciously, stinging, or squirting formic acid. Not many predators want to mess with them. Further, where there is one ant there are usually more, quick to come to the aid of a fellow worker in distress. Any insect (or even spider) that looks like an ant is probably going to be left alone by its enemies.

From previous experience, I know that small orange and brown pompilids with banded wings are likely going to be females in the genus Ageniella. I encountered the one below at the Orange Municipal Airport in Massachusetts on September 7, 2009. She was toting a spider, its legs amputated to presumably facilitate easier transport. Nick Fensler, an expert on spider wasps of eastern North America, kindly identified it for me as probably Ageniella conflicta.

Females of that species apparently hunt immature wolf spiders (family Lycosidae) as food for their larval offspring. Varacosa gosiuta, V. avara, Arctosa littoralis, and Pardosa valens are among the recorded hosts for Ageniella conflicta. Jumping spiders have also been recorded as prey, but that was before even the experts could tell conflicta from accepta.

The amputation of the legs also makes it easier for the female wasp to stuff her victims into narrow openings. The wasps dig short burrows that originate in pre-existing crevices in the soil. Little else is known of their nesting habits and life cycles.

It should be noted that males of both species look completely different from females: They are black with some reddish markings on the legs, and a white spot on the tip of the abdomen, as shown below. Neither gender is very large. The forewing length for females is 5-8 millimeters, and 4-5 millimeters for males.

Ageniella accepta visits other plants besides sunflowers, including nectaries of Chamaecrista nictitans (Sensitive Partridge Pea), and flowers of Euphorbia marginata (Snow-on-the-Mountain), Baccharis salicifolia (Seep Willow or Mule-fat), and Bifora Americana (Prairie Bishop).

Ageniella accepta ranges across most of the southern half of the United States and into Mexico. This is one of at least three North American species in the “accepta species group.” The widespread A. conflicta and the western A. blaisdelli are the others, according to Townes (1957).

The scarcity of information about our species of Ageniella means that your own observations could be quite meaningful. Next time you think you see an ant, double check and see if it isn’t actually one of these unique spider wasps.

Sources: Evans, Howard E. and Carl M. Yoshimoto. 1962. “The Ecology and Nesting Behavior of the Pompilidae (Hymenoptera) of the Northeastern United States,” Misc Publ Entomol Soc Am 3(3): 67-119.
Kurczewski, Frank E. 1975. “Host Records for Some Species of Pompilidae From the Southwestern United States and Mexico,” Pan-Pac Entomol 51(2): 147-151.
Kurczewski, Frank E. and Edmund J. 1968. “Host Records for Some North American Pompilidae (Hymenoptera) With a Discussion of Factors in Prey Selection,” J Kans Entomol Soc 41(1): 1-33
Townes, Henry. 1957. “Nearctic Wasps of the Subfamilies Pepsinae and Ceropalinae,” U.S. Nat. Mus. Bull. 209: 1-286.

Sunday, August 26, 2012

Spider Sunday: Sassacus

It is often difficult to tell whether a particular spider specimen is an adult or an immature, especially if you go by size alone and don’t know how large an adult is supposed to be. Take the jumping spider genus Sassacus for example. The adult animal is only about 3-5 millimeters (male) or 4.4-5.5 millimeters (female). The specimen pictured here is an adult female, probably gravid, that I spotted on the leaf of a sunflower plant here in Colorado Springs on July 28 of this year.

The origin of the genus name is an interesting slice of history. According to, “Sassacus” was the last chief of the Pequot Indians, a Native American tribe of the Connecticut Valley that was vanquished in a war with English settlers in 1637.

The iridescent color and very compact appearance of these spiders leads scientists to suspect that they are mimics of certain leaf beetles in the family Chrysomelidae. Many chrysomelids just don’t taste good, or they feed on poisonous plants and sequester those herbal toxins for their own defense. They advertise their distastefulness to predators with bold black and white, yellow, orange, or red color patterns, or with bright metallic colors.

Depending on which authority you consult, there are either three or nine species of Sassacus in North America, including Mexico. Richman (2008) revised the genus to include the former genus Agassa, and one species group from the genus Metaphidippus. Collectively, the genus occurs from southern British Columbia south into Central America. It is widespread in the U.S. Sassacus papenhoei and Sassacus vitis have both been collected here in Colorado.

One of the defining characteristics of this genus is the very short legs. The fourth pair of legs is the longest, followed by the third pair. The first pair of legs is still the thickest, with one or two pairs of spines, used in tackling prey. I believe the female in these images is missing one of her front legs, but if so she disguises her injury well.

Like most jumping spiders, Sassacus engages in visual courtship displays. It turns out that twitching the abdomen also produces an auditory stimulus, which scientists have recorded in the laboratory (Maddison and Stratton, 1988). Males make zigzag or spiral approaches to the female at first, raising and crossing their front pair of legs once they have a female’s attention. Later, they raise and lower their front legs until they are accepted or rebuffed (Richman, 1982).

There are some “normal” species in the genus that are more spider-like than beetle-like, but the ones you are likely to encounter are going to be the beetle mimics covered in those iridescent scales. Look for Sassacus on broadleaved plants in open fields and along forest edges, but don’t expect them to be common. I was surprised how few “popular” spider references included the genus.

Sources: Fitch, Henry S. 1963. Spiders of the University of Kansas Natural History Reservation and Rockefeller Experimental Tract. University of Kansas Museum of Natural History Miscellaneous Publication No. 33. 202 pp.
Kaston, B. J. 1978. How to Know the Spiders (Third Edition). Dubuque, Iowa: Wm. C. Brown Company Publishers. 272 pp.
Maddison, Wayne P. and Gail E. Stratton. 1988. “A common method of sound production by courting jumping spiders (Araneae, Salticidae),” Journal of Arachnology 16(2): 267-269.
Richman, David B. 2008. “Revision of the jumping spider genus Sassacus (Araneae, Salticidae, Dendryphantinae) in North America,” J. Arachnol. 36(1): 26-48.
Richman, Daved B. 1982. “Epigamic display in jumping spiders (Araneae, Salticidae) and its use in systematics,” J. Arachnol. 10: 47-67.
Richman, David B. and Robert R. Jackson. 1992. “A review of the ethology of jumping spiders (Araneae, Salticidae),” Bull. Br. Arachnol. Soc. 9(2): 33-37.

Wednesday, August 22, 2012

Wasp Wednesday: Euodynerus annulatus

Back on July 9, 2012, I visited the Florissant Fossil Beds National Monument in Teller County, Colorado. The area is well-known for amazing specimens of fossil insects, but the ones that live there now are pretty interesting, too. Take, for example, the mason wasp Euodynerus annulatus.

This species is widespread, found from coast to coast in the United States, south to Mexico; and in the Canadian provinces of British Columbia, Alberta, Saskatchewan, and Ontario (though the last record for Ontario was in 1954; and the record for Saskatchewan is very recent). There are five subspecies, three of them western in their distribution. The color and markings vary considerably among those different subspecies.

These are also fairly sizeable wasps, the length of the front wing varying from 8.5-10.5 millimeters. The species could be confused with the very common Euodynerus hidalgo, but the propodeum (hindmost segment of the thorax) is not as angulate in E. annulatus. The hind margins of the first and second dorsal abdominal segments (tergites) are also not clear and reflexed (turned up) as they are in E. hidalgo.

What surprised me the most about this wasp was learning that instead of using pre-existing cavities, or making mud nests, females of Euodynerus annulatus excavate burrows. Not only that, but they extend the tunnel aboveground as a curved mud “chimney.” Several individual cells branch from the main burrow underground. This wasp does not seem to be particular about the soil type, finding hard soil or soft soil perfectly suitable for its nest. The species does seem to favor situations close to water, as the female will regurgitate water to soften the soil during nest-building.

The chimney might help make the nest easier to defend from potential parasites, but it apparently serves as the source of mud pellets to make the final nest closure as well. Eventually, the turret is deconstructed entirely and the nest entrance made nearly invisible and flush with the surrounding soil (Rau and Rau, 1918).

The female wasps use caterpillars from the moth families Crambidae, Pyralidae, and Noctuidae as food for their larval offspring. The caterpillars are only weakly paralyzed (Rau and Rau describe some instances in which the larvae were still ambulatory), usually several placed in each cell. A single egg is suspended from a short thread attached to the wall of the cell before it is stocked with caterpillars. When all cells are provisioned, the nest entrance is sealed and the wasp leaves to begin a new nest.

Caterpillars of the genus Loxostege were recorded as a major host by Rau and Rau, and certainly the Alfalfa Webworm and its relations are exceedingly abundant here along the Front Range. Here’s what the adult moth looks like:

Male specimens of Euodynerus annulatus can be recognized by the hooked tips of the antennae, and their less robust appearance. I found both a male and female taking nectar from an early-blooming rabbitbrush plant (Ericameria sp.) at Florissant Fossil Beds.

Ironically, while no nest parasites are recorded for this mason wasp, the adult wasps are vulnerable to a type of insect called a “twisted-wing parasite,” Pseudoxenos hookeri. Parasitized wasps will have bulges in the abdomen, with what look like bullets wedged between abdominal segments. More on these bizarre animals in a future post.

I must thank Dr. Matthias Buck, Associate Curator of Invertebrate Zoology at the Royal Alberta Museum in Edmonton for identifying the wasps in these images, and describing a bit of their biology. I am hoping to get him down to Colorado at some point to see for himself the amazing diversity of Eumeninae to be found here.

Sources: Buck, Matthias, Stephen A. Marshall, and David K.B. Cheung. 2008. “Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region,” Canadian Journal of Arthropod Identification No. 5: 492 pp (PDF version).
Krombein, Karl V., et al. 1979. Catalog of Hymenoptera in America North of Mexico (volume 2 Apocrita (Aculeata). Washington, DC: Smithsonian Instititution Press. 2188 pp.
Rau, Phil and Nellie. 1918. Wasp Studies Afield. Princeton, NJ: Princeton University Press. 372 pp. (Dover edition, 1970). Note that Euodynerus annulatus is described as Odynerus geminus on pages 300-312.

Sunday, August 19, 2012

Spider Sunday: Breaking News

I was debating with myself about what species to feature in this week’s “Spider Sunday,” when I got wind of a story that immediately trumped all other options. Not only was there the formal announcement of a new species of spider, but one that represented an entirely new family of spiders as well. It takes a very unique species to demand its own family, but this arachnid is strange indeed.

Several press outlets carried the story, many including images of this odd spider. Not surprisingly, there is some conflicting information and perhaps exaggeration.

What is known for certain is that the spider had to be formally described and named before the discovery could be made public. That official record is in the latest issue of the professional journal ZooKeys, a peer-reviewed online publication of Pensoft Publishers. This in itself is newsworthy. Online journals shrink the timeline between discovery of species and the broadcast of those discoveries. Even so, this spider was found initially in 2010. Online journals also mean that you don’t have to live next to a university library to be able to access authoritative serial publications.

Let’s get back to the spider, though. What makes it unique? There is no question that the most distinguishing feature is the long, articulated, blade-like claws on the tip of each leg. The spiders are found on the ceiling of caves in southern Oregon (one report included northern California and British Columbia in the distribution), suspended upside down in very small, minimalist webs. It is thought that they wait for small, flying insects to come within range of their lanky legs, then hook their prey with those sickle-like claws.

These are not small animals. The legspan of a mature specimen can exceed two inches (five centimeters). As scientist Charles Griswold, the lead author in the journal article, explained in a BBC radio interview, they look even larger in the beam of a headlamp. The spiders are not blind, but have only six eyes as opposed to the usual eight for most spiders. Live specimens in Griswold’s lab at the California Academy of Sciences refused to eat.

The last time a new species of spider required the erection of a new family was back in 1990, when a South African spider was described. You have to go back to the 1890s to find the last time a new family of spiders was established for a North American spider.

The new family is named Trogloraptoridae. The spider’s official species name is Trogloraptor marchingtoni. The genus name is a combination of Greek and Latin that translates to “cave robber.” The species is named for Neil Marchington, a deputy sheriff for Deschutes County, Oregon, who first showed scientists the spiders inside a cave. Marchington is also a member of the Western Cave Conservancy and an amateur biologist.

Cave organisms in general are poorly understood, and highly vulnerable. Populations of cave animals tend to be small, specifically adapted to a lightless habitat, and prone to perish with the slightest change in that environment. It is largely thanks to the efforts of organizations like the Western Cave Conservancy that any effort at all is made to preserve and protect caves. Irresponsible spelunkers (cave explorers) can easily damage a cave just by touching formations and thereby changing the chemistry that forms caves. Vandals can deface and destroy caves; and development above a cave can result in contamination of groundwater that courses through the cave, if not causing the cave to collapse in part or in its entirety.

I take special delight in learning that this new species was found in my home state of Oregon. The coniferous forests there have relatively poor biodiversity compared to deciduous forests, deserts, and rainforests, but there is no argument that the species found in the Pacific Northwest are often unique. I hope to get back there again in the future, if only to find insects and spiders that I know exist there, but that I have never seen. I’ll have to add this spider to that list!

Wednesday, August 15, 2012

Wasp Wednesday: Mesostenus

I am finding a great diversity of wasps (and other insects) visiting the leaves and stems of sunflowers (Helianthus spp.) this summer here in Colorado Springs. Among them is an ichneumon wasp in the genus Mesostenus. Boldly marked in black, white, and red, they are difficult to miss despite their small size (about 6-13 millimeters in the specimens illustrated here).

Sunflowers have special structures called “extrafloral nectaries” that secrete a sweet liquid that insects crave, especially ants. The ants try and drive off every other competing insect, which is mostly wasps, bees, and flies. Some plants are more attractive than others, and the reasons for that are probably many. We have had a sustained drought here on the Front Range, verging on the “extreme” side of the scale. Record-breaking hot temperatures have also withered many annual plants. It is metabolically expensive for sunflowers to produce the nectar, so some individual specimens probably forgo the production process. This leaves them at least slightly more vulnerable to herbivorous insects that the ants would normally fend off along with the flies and wasps.

Because the wasps are constantly dodging the ants, it is difficult to get good images of them. They are persistent, however, and may eventually settle down long enough for me to get a clear shot while they lap up the sunflower’s exudates. At least it is easy to tell the difference between the females and males. Mesostenus is one of the many genera in the Ichneumonidae where the female possesses a long, tail-like egg-laying organ called an ovipositor. Males (below) lack an ovipositor, obviously.

Many people mistake the ovipositor for a stinger, and react with alarm to a wasp that looks like it could penetrate a down jacket with its venomous weapon. The device is instead employed to lay eggs in the host insects the wasps parasitize.

There are ten species of Mesostenus in North America north of Mexico, but the genus is nearly worldwide in overall distribution. About four of those species can be found in Colorado. M. sicarius is closely tied to certain cacti (Opuntia spp.), of which we have prickly-pear here in the Springs.

The long ovipositors come in handy when inserting an egg in a stem-boring or shoot-boring caterpillar like that in the genus Acrobasis, in the moth family Pyralidae. The wasps are also important parasites of stored product pests like the Indianmeal Moth, Plodia interpunctella, also in the Pyralidae. The American Plum Borer, Euzophera semifuneralis, has caterpillars that feeds beneath the bark of host trees, a habit that still leaves them vulnerable to Mesostenus gracilis, the species that might be shown here. Not surprisingly, the caterpillar of the Sunflower Moth, Homoeosoma electella, is also a host. Mesostenus also parasitizes caterpillars of the moth families Crambidae and Tortricidae.

We only know host associations for a few of these wasps, so rearing caterpillars may yield new host records. That is true for other Ichneumonidae as well. Folks who try raising caterpillars through to moths or butterflies are often profoundly disappointed when a wasp (or fly) emerges from the larva or chrysalis instead. I urge people to take care to preserve the insect anyway, noting the species (or genus or family) of caterpillar from whence it came. It could turn out to be a valuable observation.

Sources: Carlson, Robert W. 2009. “Database of Hymenoptera in America North of Mexico,”Discover Life.
Cushman, R.A. 1929. “A Revision of the North American Ichneumon-flies of the Genius[sic] Mesostenus and Related Genera,” Proc U S Nat Mus 74(2761): 1-58 (Smithsonian Digital Repository, available as a PDF).

Tuesday, August 14, 2012


I want to say a heartfelt "thank you" to all of you who are following this blog. When I don't feel much like writing a post, you are the inspiration. I don't want to let my audience down! Don't hesitate to suggest topics you want to know more about; comment on existing posts as often as you like.

It is also a great comfort to know that I am not the only one curious about the lives of the animals that exist outside the realm of most human sentiment. It gives me hope when I make another "convert." Thank you, I look forward to carrying on.

Sunday, August 12, 2012

Spider Sunday: Spider Workshop

Last Friday night, Heidi and I went to Cheyenne Mountain State Park, just south of Colorado Springs, to hear a presentation on the Western Prairie Rattlesnake. Besides learning a lot about that reptile, we learned that there was going to be a workshop on spider identification the next day (yesterday), from 1-5 PM. Heidi had to work at the zoo, so I took the bus as far as I could go and walked the last four miles to the park. It was well worth the effort.

This is the second year that Dr. Paula Cushing, Curator of Invertebrate Zoology at the Denver Museum of Nature and Science, has held a spider workshop at Cheyenne Mountain State Park. Dr. Cushing seeks to promote a better public understanding of arachnids in general, and hopes to recruit volunteers to help with the Colorado Spider Survey, an ongoing project to document the distribution of the state’s spider fauna. She delivers a highly informative introduction to spider anatomy, diversity, and biology with liberal doses of humor.

Each participant in the workshop paid $5.00 for a handbook that includes a key to the spider families found in Colorado, and documents that essentially deputize us to collect spiders on certain public lands on behalf of the survey. But wait, there’s more. We also got a collecting kit that included a dry collecting vial plus two vials of alcohol into which we were to deposit our specimens.

Once we were coached in the best methods for collecting spiders, we dispersed from the Camper Services Building into the field to try our luck.

A brief shower earlier in the afternoon did not deter us from turning over rocks (where I found a gnaphosid spider that ultimately escaped), sweeping the tall grasses and herbs with sturdy nets, and beating the trees with beating sheets (note to self: Do not use a beating sheet on a windy day unless you want to be taken aloft somewhere). We collectively found at least eight (count ‘em, 8) families of spiders in only forty minutes of searching.

We took our catch back into the building and Dr. Cushing put some of the specimens under a microscope so we could better observe the different characters that define the various families of spiders. Here she is putting a juvenile Western Black Widow in view.

The preparation that went into this workshop was quite impressive. Dr. Cushing and one of her former students are to be commended for offering such a program. I would encourage other expert arachnologists to do similar public outreach. The benefits are many: You can change people’s attitudes, vanquish myths and stereotypes, and garner support for your research. People woefully underestimate the positive impact of spiders in the natural world, and the potential of spider silk and venom to advance technology and medicine respectively.

I will have to start taking vials with me again when I am in the field. Collecting spiders for research purposes helps increase our understanding of their species, and under most circumstances (cave and dune fauna excepted, perhaps) does not impact their populations.

Thanks also go to the administrators, naturalists, and volunteers at Cheyenne Mountain State Park for encouraging such informative activities as this workshop, and then participating in them as well.

Wednesday, August 8, 2012

Wasp Wednesday: A Real Surprise

I am certainly finding the Front Range region to be exceptionally diverse when it comes to wasps, but nothing could have prepared me for what I found in the field yesterday, August 7. I was looking over a White Sweet Clover (isn’t there a song about that?), when a very large wasp commanded my attention. I immediately recognized it as a paper wasp, but not a species I would have expected in Colorado Springs.

This is a male specimen of Polistes carolina or Polistes perplexus. Either way, it is most likely going to turn out to be a county record, potentially a state record, and perhaps even a range extension. Both species are recorded for Kansas, so what is a couple hundred more miles or so?

I also managed to collect the specimen, so I’ll be able to eventually examine it under a microscope for the details necessary to separate the two species. Until very recently, it was thought that the males could not be distinguished at all, but apparently there are transverse (horizontal) ridges on the propodeum (hindmost segment of the thorax) that are weak in P. carolina and much more evident in P. perplexus. Watch this space for the final determination of the species.

For now, I’m ecstatic over this discovery. I’d sure like to find the nest this fellow came from. Females are a little easier to identify, and finding the nest would verify that this is a species breeding here. Even so, this male is in immaculate condition, suggesting it did not travel a long distance.

Because these two species were once thought to be a single species (P. carolina), most documentation of their biology is somewhat suspect. Polistes carolina apparently nests in exposed situations, such as under the eaves of buildings, for example; and reports of that species nesting in hollow trees and other protected locations actually apply to Polistes perplexus. Prey is probably similar in both species, consisting mostly of caterpillars chewed up by the adult wasps and fed to the larvae in the nest. Still, wasps this large can probably tackle much larger prey, and a single record of an attack on a cicada (Tibicen auletes) could be for either species of wasp.

I find that in current literature the size of these wasps is measured by the length of the forewing, which is 15-20.5 millimeters in P. carolina, and 17-21.5 millimeters in P. perplexus. Contrast this with the measurements of the abundant and widespread Northern Paper Wasp, Polistes fuscatus. Forewing length for that species averages between about 13 and 17 millimeters.

Polistes carolina is most common in the southern U.S., but ranges from New York, Pennsylvania, and Ohio south to Florida and west to Illinois, Kansas, Arkansas, and eastern Texas. There is one record for Ontario, Canada, but the species is not established there. That could be the case here in Colorado, too: a fluke. P. perplexus ranges from Maryland to Georgia, and west to southern Illinois, Kansas, Oklahoma, and Texas. One recent record has come from Pennsylvania.

Keep your own eyes open for species that seem “misplaced.” Interstate (and international) commerce, climate change, and other factors are changing the distribution patterns and abundance of many species. We also haven’t looked that closely at insect species with little or no economic impact. You stand a good chance of adding to our collective knowledge with relatively minimal effort.

Source: Buck, Matthias, Stephen A. Marshall, and David K.B. Cheung. 2008. “Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region,” Canadian Journal of Arthropod Identification No. 5: 492 pp (PDF version).

Monday, August 6, 2012

Time to Delete "Moth" From Our Vocabulary

I recently learned of a controversial theory of metamorphosis that got me thinking about moths and butterflies. More on that later. Perhaps National Moth Week also had something to do with my thought process, and/or a Facebook post by a friend purporting a difference between moths and butterflies. Folks, there is no such thing as a difference between moths and butterflies.

There is no difference between moths and butterflies that does not have exceptions:

  • Moths have feathery antennae. This is a myth. A few do, the males’ more “feathery” than the females’, the better to detect her pheromones wafting on the winds. Most moths have filamentous (hair-like) antennae.
  • Moths are active at night. Hogwash. Most species are nocturnal, but there are plenty that fly during the day. Many fly both day and night. There are some butterflies that are nocturnal for that matter. I have personally seen some hairstreak butterflies attracted to lights at night.
  • Moth caterpillars spin cocoons. Hardly any moth caterpillars spin cocoons, actually. Most simply have a naked pupa (the term “chrysalis” could also apply), often underground, sometimes inside a gallery the caterpillar bored in dead wood or living stem, stalk, or root. A cocoon does help insulate a pupa in exposed situations during weather extremes, so some species add this silken covering.
  • Moths eat clothing. There is so much wrong with that statement I’m not sure where to begin. The larvae (caterpillars) of some moths do consume dried animal products like wool garments and blankets, but they are in an extreme minority. The feeding habits of the vast majority of moth caterpillars are of no consequence to people whatsoever.

It is that last item that hints at the real reason we insist on an artificial distinction between moths and butterflies. We need a villain, and the moth is it. Butterflies can do no wrong! They are colorful and carefree and their larvae eat weeds we don’t like. Moths are evil, their caterpillars consuming our crops and ravaging our forests. Moths are black, brown, or gray, and hide themselves in shame by day, only daring to emerge under the cloak of darkness that is night.

Moth Week may have started to peck away a little at the mythology of moths, but we should consider banishing the term “moth” from our lexicon altogether. Science recognizes that weevils, “ladybugs,” and “fireflies” are all types of beetles. Mosquitoes, gnats, and no-see-ums are acknowledged as types of flies. Moths are butterflies, by virtue of the fact that they are in the same order: Lepidoptera.

The theory of metamorphosis that made it onto National Public Radio implies that it isn’t butterflies and moths that are different, but the adult stage and the caterpillar stage. So different are they that perhaps they are separate species merged into one being. The caterpillar leads an entirely different lifestyle than the adult, and “dies” during the pupal stage, only to be “resurrected” as a new, winged creature at the conclusion of the life cycle. Yes, the majority of the scientific community scoffs at this idea, perhaps rightly so, but one can argue that the similarities between adult butterflies and moths are much smaller than the differences between the larva and adult of any one species.

Moths need positive attention for many, many reasons:

  • Scores of moth species are endangered, or have populations that truly border on unsustainable. Contrast that with the “sky is falling” cries from butterfly conservationists every time there is the slightest slump in populations of hibernating Monarch butterflies.
  • Moths are true pollinators, while butterflies (and many moths, to be fair) are merely “flower visitors.” Female yucca moths (family Prodoxidae) intentionally stuff a wad of pollen into the stigma of the host plant, thereby fertilizing it. The moth does this because her caterpillars require viable yucca seeds on which to feed. The caterpillars rarely consume the entire seed set, and both host and herbivore prosper. Several tropical orchid species rely solely on certain sphinx moths for pollination.
  • Moths are incredibly important to the food chain. Countless birds, bats, even grizzly bears, rely on moths as a food source. Oh, add fish, reptiles, amphibians, spiders, and other insects to that list. Many of those predators are in fact moth specialists. Some spiders even mimic the pheromones of certain female moths to attract the male moths to their webs.

It is time to call “moths” what they really are: butterflies. Time to stop discriminating based on assumptions, myths, and preconceived notions of what moths should be. Reality is far more subtle, and nature lacks the anthrocentric lens we view Her through. Our vocabulary should reflect that reality, and not our prejudice, cynicism, and biases. Who is with me?

Sunday, August 5, 2012

Spider Sunday: Sixspotted Orbweaver

I like to investigate sunflowers (Helianthus sp.) at this time of year because the plants’ extrafloral nectaries attract a variety of wasps, flies, and other insects. Not surprisingly, predatory insects stake out sunflowers, too, taking advantage of the abundance of potential prey. One of those predators that I found the other day was a Sixspotted Orbweaver, Araniella displicata.

This particular specimen was the color of a sunflower, too, with a bright yellow abdomen. Other specimens, as illustrated throughout this post, may be nearly pure white, or infused with varying degrees of rust red, especially in immature specimens. The species does maintain a consistent pattern of three (sometimes four) pairs of black dots along the edges of the rear half of the abdomen.

The Sixspotted Orbweaver is one of the most widely-distributed arachnids in North America, found over virtually the entire continent, including parts of Alaska. It is not uncommon in gardens and yards, but neither is it conspicuous. Adult females measure only 4-8 millimeters in body length, males 4-6 millimeters.

Most orb weavers spin fairly large webs in proportion to their own body size, but not so with Araniella displicata. The web of an adult spider may be only three or four inches in diameter. The spiral snare is usually built well off the ground (four to six feet), and often oriented in the horizontal plane, frequently spanning the edges of a single large leaf. The spider sits in the center (hub), hanging beneath a horizontal web (as in the image above), or head-down in a vertical one. Webs spun across the edges of a leaf may intercept and entangle longlegged flies (family Dolichopodidae), and other insects that habitually skitter over the surface of a leaf and then take flight to another piece of foliage.

Sixspotted Orbweavers overwinter as subadult spiders, reaching adulthood in late May or early June (probably earlier in the more southerly climates). Mating takes place at about that time, and female spiders make egg sacs shortly thereafter. The egg sac contains an average of 80 eggs and is covered in loose, fluffy, yellowish silk. The package may be deposited in a curled leaf that also serves as the mother’s retreat on the perimeter of the web.

Interestingly, while this species tends to frequent woodland habitats in North America, it is found mostly in heath and heather fields in Britain, where it also occurs. The species ranges over much of northern Europe but is considered rather uncommon or even rare.

The next time you find a “baby” orb weaver, be sure and check to see if it might not actually be an adult of Araniella displicata. Mature ones can be found from late spring to nearly the end of summer. After that, you will find juveniles.

Sources: Howell, W. Mike and Ronald L. Jenkins. 2004. Spiders of the Eastern United States: A Photographic Guide. Boston: Pearson Education. 362 pp.
Weber, Larry. 2003. Spiders of the North Woods. Duluth, Minnesota: Kollath+Stensaas Publishing. 205 pp.

Wednesday, August 1, 2012

Wasp Wednesday: Bembecinus

Once again, just last Saturday, July 28, I found myself baffled by a little wasp I found excavating a burrow in some sand not far from my home. I took images and, realizing that I didn’t recognize it, began the identification process. I started with something it reminded me of: a small Bicyrtes species. I then went up the classification ladder on How about the subtribe Bembecina? Not really, though Microbembex was close. Was it in the tribe Bembicini at least? Yes, that seemed like a safe bet. Browsing the images for the subtribes I found myself surprised that the Stizina looked promising. Indeed, it turns out I had been observing a female wasp in the genus Bembecinus.

The characters I found key to making the ID included the eyes, which are strongly convergent at the bottom of the face, and strongly divergent at the top of the head. The second submarginal cell in the front wing is petiolate or nearly so.

I thought I had lost my opportunity to photograph this wasp right off the bat. I made a quick move while she was down her burrow, but she popped back out quickly, saw me, and flew off. Luckily, she was determined to finish what she started, and returned shortly to continue digging. She would occasionally fly off, only to return a short time later, regardless of my presence or movements. At one point a tiny, curious ant walked into her burrow while she was inside it, and she literally kicked it out of her tunnel.

Good thing for the ant that female Bembecinus hunt leafhoppers (Cicadellidae and related families) as food for their larval offspring. Rather than stockpiling several prey and then leaving the larva to feed, Bembecinus practices an advanced form of parental care called “progressive provisioning.” She lays her egg in the empty cell at the end of her burrow, and then brings food to the larva on an as-needed basis. She can deliver, too. Researchers have recorded different species bringing in from 71 to 757 prey items to a single nest. One assumes the larger the prey species the fewer it takes to feed the wasp larva, but that is still a staggering amount of work for the mother wasp.

The burrow is eventually sealed permanently at, or before, the time the larva enters a pre-pupal stage. The female then begins the nesting process over again. Bembecinus is often highly gregarious, several to many individual females nesting in a small area. Indeed, I did find another specimen (though perhaps a different species) nesting nearby the first.

Interestingly, males of some species of Bembecinus actively dig to reach pre-emergent, virgin females. These males have short “tarsal rakes” of spines on their front feet, so may be mistaken for females themselves. They are among the most competitive of wasps when it comes to mating, and males may physically fight over a female at any point, including when another male is already coupled with a female.

Both genders gather in “sleeping clusters,” sizeable balls of wasps situated on twigs, stems, or foliage of plants near the nesting area. The clusters can be all males early in the season, and all females late in the season, though this varies with the species and maybe even the geographic area.

Bembecinus is not immune to nest parasites. Velvet ants (family Mutillidae), and cuckoo wasps (Chrysididae) have been recorded as parasites for different species of Bembecinus around the globe. Surprisingly, no fly parasites have been documented. Satellite flies in the family Sarcophagidae are insidious pests of most all other burrowing wasps, so this is a mystery.

There are currently ten species of Bembecinus listed for North America north of Mexico, collectively found across most of the continent. Approximately 190 species are known worldwide, on all continents but Antarctica. The specimens I was watching measured an estimated 8-10 millimeters in size, but some species are larger and others smaller.

I may have to go back and see if I can find more of these interesting sand wasps. I hear they are even active on extremely hot days, and we have had a lot of those this year in Colorado Springs.

Sources: Evans, Howard E. 1966. The Comparative Ethology and Evolution of the Sand Wasps. Cambridge, Massachusetts: Harvard University Press. 526 pp.
O’Neill, Kevin M. 2001. Solitary Wasps: Behavior and Natural History. Ithaca: Comstock Publishing Associates (Cornell University Press). 406 pp.