Wednesday, June 27, 2012

Wasp Wednesday: Elm Sawfly

Finally! I have been looking for an adult Elm Sawfly, Cimbex americana, for decades, ever since seeing pinned specimens in college back in the early 1980s. My quest ended this past Monday, June 25, when I happened upon a huge male specimen in the middle of a meadow in Emerald Valley, Colorado.

The Elm Sawfly is a large, robust insect about 20-25 millimeters in body length. They appear even bigger, especially the males with their beefy “thighs” (femora) on the middle and hind legs. The jaws of both genders are strong, and used to strip bark from twigs, sometimes girdling them in their efforts to reach the tasty sap. The clubbed, relatively short antennae are a characteristic of all members of the family Cimbicidae. The overall plump appearance often convinces people that these insects are bees rather than wasps.

The larvae of these wasps feed not on pollen, nectar, or other insects paralyzed and provided by their mothers. Instead, sawfly larvae feed on plant foliage. Despite the name “Elm Sawfly,” Cimbex americana feeds on other trees as well, especially willow, but occasionally on basswood (linden), birch, poplar, alder, and maple. At maturity, the caterpillar-like larva can be two inches (43 millimeters or so) long.

How do you tell a sawfly larva from the caterpillar of a butterfly or moth? True caterpillars have no more than five (5) pairs of prolegs, the “false legs” along the length of the abdomen that look like suction cups. Sawfly larvae have seven (7) pairs of prolegs.

When they are disturbed, Elm Sawfly larvae coil themselves and prepare to release volatile chemicals from glands in the thorax if necessary for their self-defense. They also rest in a coiled position. The rough, pebbly texture, and black midline dorsal stripe help to identify these greenish, yellowish, or whitish larvae. Look for them mostly between June and October, but note that I found the specimen pictured here on May 7 in South Carolina.

The mature larvae crawl to the ground and spin a tough, papery cocoon around themselves amid leaf litter or just below the surface of the soil. There they remain as larvae through the winter, pupating the following spring. There is only one generation per year.

The adults are sexually dimorphic in color. Shown here is a male. Females have the abdomen black with yellow horizontal bands interrupted in the middle. There is some variation in color and pattern from one geographic area to another. This is a very widespread insect, found in the U.S. and Canada from the Atlantic seaboard to the Rocky Mountains, and also the Pacific coast states north to Alaska.

Females of the Elm Sawfly use a saw-like ovipositor to insert eggs in the leaves of the host tree. They do not have a stinger. Both genders simply look intimidating. Males may defend territories. The one I found on Monday I startled from its perch, but after a wide orbit it flew right back to that one shrub, elevated only a little above surrounding vegetation.

The Elm Sawfly does have its enemies, including an egg parasite, Trichogramma minutum, a very tiny type of wasp. A large ichneumon wasp, Opheltes glaucopterus barberi, is an internal parasite of the sawfly larva. The sarcophagid fly Boettcheria cimbicis has been reared from the pupal cocoons of the Elm Sawfly.

See if you can find this species in your own region. Do you find it to be common? Do populations vary from year to year? While this species is rarely a pest (it has been known to defoliate shade elm trees, especially in the northern Midwest), it would pay to know more about it.

Sources: Drooz, Arnold (editor). 1985. Insects of Eastern Forests. Washington, DC: U.S. Department of Agriculture, Miscellaneous Publication No. 1426. 608 pp.
Essig, E. O. 1958. Insects and Mites of Western North America. New York: The Macmillan Company. 1050 pp.
Furniss, R. L. and V. M. Carolin. 1977. Western Forest Insects. Washington, DC: U.S. Department of Agriculture, Miscellaneous Publication No. 1339. 654 pp.
Stein, John D. 1974. Elm Sawfly. Forest Pest Leaflet 142. Washinton, DC: U.S. Forest Service, U.S. Department of Agriculture.

Sunday, June 24, 2012

Spider Sunday: Beach Wolf Spider

Life is literally a beach for the Beach Wolf Spider, Arctosa littoralis. This member of the family Lycosidae ranges throughout the United States and southern Canada, so obviously not all individuals live by the seaside. However, this spider is partial to sandy habitats such as dunes, stream banks, and blowouts.

The specimen shown here is one I encountered in Massachusetts on Cape Cod National Seashore under cover of darkness on July 25, 2009. It had killed what was probably an already weak worker honeybee. This worked to my advantage because the arachnid was not racing across the sand, outrunning me, my light source, and camera.

Arctosa littoralis is a fair-sized spider, mature males and females measuring 11-15 millimeters in body length. Their sprawling legspan adds to their perceived size. Still, good luck spotting one if it isn’t moving. The camouflage of this species is amazingly effective. Mottled gray, brown, or nearly white, it blends in with the sandy substrate upon which it hunts.

It may help to look for them at night. Arm yourself with a good headlamp or flashlight, held at the same level as your eyes. When the beam of light hits a wolf spider, the animal’s eyes will glint with a bluish-green shine. This technique works on other wolf spiders, too, and a female with young on her back looks like a diamond-studded stone. You will be surprised at just how populous lycosids are if you ever try this. I tried it on a lawn in south Texas once. I thought the grass was covered in dew. No, just wolf spiders!

Should you opt to seek the Beach Wolf Spider by day, try turning over driftwood and other debris on the shore. The spiders hide in such situations by day; they may also dig burrows in the sand, so look for that as well.

Despite being a swift, muscular hunter with excellent vision, Arctosa littoralis is not immune from its own predators. Several species of spider wasps in the family Pompilidae are recorded as using the Beach Wolf Spider as food for their larval offspring. Priocnemis cornica, Ageniella conflicta, and Anoplius apiculatus are among the pompilids that prey on Arctosa littoralis.

Summer is here, and vacation time is upon us. Consider looking for the Beach Wolf Spider and other seashore invertebrates during your next leisure trip to the beach. Don’t forget to pack your sunscreen and shades, though.

Wednesday, June 20, 2012

Wasp Wednesday: The Wasp Tree Part II

Last week I wrote about a single, blooming Saltcedar tree (Tamarix sp.) that was attracting a great diversity of insects, especially wasps. Well, after spending several more days at that (introduced, invasive) tree, I can add to the list significantly.

The butterflies alone now include Checkered White, Orange Sulphur, Dainty Sulphur, Gray Hairstreak, Acmon Blue, Reakirt's Blue, Painted Lady, American Lady, Variegated Fritillary, American Snout, Common Checkered Skipper, Common Sootywing (image above), and Uncas Skipper (identification tentative). Bees include the following families: Colletidae, Apidae, Megachilidae, and Halictidae.

The following list of wasps will be the final one. I will amend it as I make more specific identifications, and/or add new species during future forays to the tree:

  • Argidae: Argid sawflies
  • Braconidae: Braconid wasps
  • Ichneumonidae (Ichneumon wasps)
  • Chalcididae (Chalcid wasps):
  • Brachymeria sp. (chalcid wasp)
  • Leucospidae (Leucospid wasps):
  • Leucospis sp.
  • Chrysididae: Cuckoo wasps

  • Scoliidae (Scoliid wasps):
  • Campsomeris sp.
  • Trielis octomaculata
  • Tiphiidae (Tiphiid wasps):
  • Myzinum sp.

    Myzinum male

    Myzinum female

  • Mutillidae (Velvet ants):
  • Dasymutilla sp.
  • Vespidae (social wasps, mason wasps):
  • Polistes dominula (European Paper Wasp)
  • Polistes aurifer (paper wasp)
  • Vespula sp. (yellowjacket)
  • Eumenes sp. (potter wasp)
  • Euodynerus spp. (mason wasps)
  • Parancistrocerus? sp. (mason wasp)
  • Pompilidae (Spider Wasps):
  • Hemipepsis ustulata (“tarantula hawk”)

  • Cryptocheilus sp.
  • Anoplius spp. (spider wasps)
  • Poecilopompilus interruptus (spider wasp)
  • Sphecidae (Sphecid Wasps):
  • Sceliphron caementarium (Black & Yellow Mud Dauber)
  • Chalybion californicum (Blue Mud Dauber)
  • Sphex lucae (katydid hunter)
  • Isodontia elegans (grass-carrier wasp)
  • Prionyx spp. (grasshopper hunters)
  • Podalonia spp. (cutworm hunters)
  • Ammophila juncea (caterpillar hunter)
  • Ammophila wrightii (caterpillar hunter)
  • Crabronidae (Crabronid Wasps):
  • Sphecius grandis (Western Cicada Killer)
  • Tachytes spp. (sand-loving wasps)
  • Bembix sp. (sand wasp)
  • Stictiella pulchella (sand wasp)
  • Steniolia elegans (sand wasp)

  • Bicyrtes sp. (stinkbug hunter)
  • Astata sp. (stinkbug hunter)
  • Dryudella sp. (true bug hunter)
  • Stizoides renicinctus(image below, blog coming soon)

  • Oxybelus sp. (fly hunters)
  • Clypeadon sp. (harvester ant hunter)
  • Aphilanthops sp. (“ant queen kidnapper”)
  • Philanthus gibbosus (“beewolf”)
  • Philanthus ventilabris(“beewolf”)
  • Philanthus spp. (“beewolves,” at least two other species)
  • Cerceris spp. (weevil wasps)
  • Eucerceris sp. (weevil wasp)

All of the above were found either on the tree or in very close proximity. Male wasps take advantage of the fact that females will seek nectar at an isolated shrub and then create territories around it which they defend from other males. I found this was especially true of Tachytes and Philanthus, but I observed other wasps (and flies, too), mating on or close to the tree.

I have put together a “set” of images on my Flickr photostream entitled “Wasp Tree” that illustratse more of these insects. It is an ever-growing set, so please visit often. Thank you.

Sunday, June 17, 2012

Spider Sunday: Mother Wolf Spider

Last Sunday was Mothers’ Day, but if you will forgive me I would like to pay tribute to arachnid mothers today. During my trip to South Carolina in early May, I had the occasion to momentarily observe a large female wolf spider of the genus Hogna on the afternoon of May 6, 2012. She had an egg sac and was living in a burrow on a wooded embankment adjacent to a road. I had stopped along with members of the Dragonfly Society of the Americas to look around a stream for dragonflies and damselflies. Descending the steep slope to get to the watercourse, another member of the party spotted the spider.

The arachnid was out of her burrow and standing on a network of threads just outside its entrance. The footfalls of others caused her to dash back into her refuge and I thought I’d seen the last of her.

I waited patiently next to her lair and was surprised when she returned to the lip of the burrow shortly. I was hoping she would climb back out for more photo opportunities, but instead she did something remarkable. She turned around inside her burrow and backed out to the entrance.

Why would a large wolf spider, with quite excellent vision, and perfectly capable of defending herself with her fangs, choose to present her vulnerable abdomen, and the egg cocoon attached to it, to potential lurking enemies? The only logical explanation that came to mind was that she was sunning her egg sac.

Indeed, there was filtered sunlight streaming through the forest canopy in the late afternoon: not too intense as to cook the ova within her silken package, but warm enough to help incubate the eggs. Still, had she not repeated this behavior, turning around at one point to make sure no threat was present and then backing out again, I’m not sure I would have believed what I was seeing.

It turns out this kind of behavior is not unheard of in other wolf spiders. Studies of Pardosa wolf spiders of two species revealed that at least one of them seeks open areas in which to expose the egg sacs to the sun (Buddle, 2000).

Had I been able to return to the site day in and day out, I would have eventually witnessed the mother spider cracking open her egg sac, allowing the newly-hatched spiderlings to emerge. Wolf spider babies crawl from the egg sac onto their mother’s back, completely covering her abdomen and sometimes much of her cephalothorax as well. She will transport the youngsters until their next molt, after which they disperse to live freely on their own.

Such devoted parental care is considered uncommon among spiders, but the more we learn the more the picture changes. There are even some female spiders that die immediately after their spiderlings hatch, offering their bodies as their offspring’s first meal.

A piece of long-standing advice is to “stop and smell the roses,” but it also pays to stop and observe animals, too. Science knows very little of the lives of most organisms that are not economically important, be they food sources or pests. Who knows what could come from your own casual observations of the insects, spiders, and other wildlife that share your yard, garden, and neighborhood park?

Source: Buddle, Christopher M. 2000. “Life History of Pardosa moesta and Pardosa mackenziana (Araneae, Lycosidae) in Central Alberta,” The Journal of Arachnology 28: 319-328.

Wednesday, June 13, 2012

Wasp Wednesday: Wasp City

Wasp-watching is better around some places than it is others. Yesterday, June 12, I happened upon a lone, blooming Saltcedar tree in the middle of a huge vacant plot of land here in Colorado Springs. In a few hours I saw a greater diversity of wasps than I had seen up until then in all the time I’ve spent here.

Unfortunately, Saltcedar, also known as Tamarisk (Tamarix sp.) is an invasive plant. It is native to Eurasia and Africa and was brought to North America as an ornamental tree sometime in the early 1800s. It can grow in a variety of habitats but seems to favor disturbed situations, riparian corridors, and moist pastures. It has deep taproots that can reach low water tables, interfering with natural aquatic systems. It is also tolerant of high salinity. Efforts have been made to eradicate it, but with little success. One tactic has been the introduction of a leaf beetle, Diorhabda elongate, and a mealybug (Trabutina mannipara), to eat the plant into submission.

Say what you will about the negative impacts of this tree, but it certainly attracts a variety of butterflies, bees, wasps, flies, and beetles that seek nectar at its profuse pale pink blossoms. Yesterday I spotted Painted Lady, American Lady, Variegated Fritillary, Checkered White, Orange Sulphur, Dainty Sulphur, and Gray Hairstreak butterflies. There were also a variety of tachinid flies, thick-headed flies, syrphid flies, and flesh flies. Robber flies hung around to prey on the pollinators. Sweat bees, leafcutter bees, resin bees, digger bees, honeybees, bumble bees, and cuckoo bees were there, too.

The above list is just the tip of the iceberg. The wasps were even more amazing in their diversity:

  • Argidae: Argid sawflies
  • Braconidae: Braconid wasps
  • Chrysididae: Cuckoo wasps
  • Vespidae: (Vespid Wasps)
  • Polistes dominula (European Paper Wasp)
  • Euodynerus spp. (mason wasps)

  • Stenodynerus? sp. (mason wasp)
  • Pompilidae (Spider Wasps):
  • Hemipepsis ustulata (tarantula hawk)
  • Cryptocheilus sp.
  • Sphecidae (Sphecid Wasps):
  • Sceliphron caementarium (Black & Yellow Mud Dauber)
  • Sphex lucae
  • Podalonia spp. (cutworm hunters)
  • Ammophila spp.

  • Crabronidae (Crabronid Wasps):
  • Sphecius grandis (Western Cicada Killer)

  • Tachytes spp. (sand-loving wasps)
  • Bembix sp. (sand wasp)
  • Clypeadon sp. (harvester ant hunter)
  • Philanthus spp. (“beewolves,” at least four species)
  • Cerceris spp. (weevil wasps)

The tarantula hawk and cicada killer were somewhat surprising. I’m going back right now to see what else I can find, and try and get better images. Take a look around your own yard, garden, neighborhood, and parks, and see what flowers you can find that draw the most wasps, bees, and other pollinators. Share your findings here if you will.

Sunday, June 10, 2012

Spider Sunday: Goldenrod Crab Spider

There are few terrestrial invertebrate animals that can change color at will, but females of the Goldenrod Crab Spider, Misumena vatia, are among them. This chameleon-like quality is just one fascinating aspect of the life of this amazing arachnid.

I should say that while the spiders can turn from white to yellow, or vice versa, this transformation is not instantaneous. It takes from one to twenty days to achieve. The result is quite miraculous in that the spider will end up virtually indistinguishable from the flower upon which it sits. Many a time I have watched one of these spiders materialize from blossoms right before my eyes.

This flower disguise helps these patient ambush hunters to capture prey consistently. The females need to be efficient because their lifespan is relatively short and they need to produce a good clutch of eggs to ensure a future generation. A female puts on about 85% of her body weight after she matures. Her eggs account for most of that mass, of course.

Despite the fact that spiders have an exoskeleton, the cuticle is incredibly elastic. Her abdomen can easily expand to accommodate a large meal and/or her developing ova.

The flower crab spider is small but mighty. Adult females measure 6-11 millimeters in body length, but their strength exceeds what you would expect. Misumena is capable of taking down some impressive, well-defended prey like the honeybee in the above image. I actually found the spider by noticing the awkward posture of the honeybee first. The Boulder Raspberry blossoms were certainly getting a lot of attention from pollinators, so the spider picked a prime hunting ground (on Cheyenne Mountain near Colorado Springs, Colorado).

Even more stunning, I came across another specimen, this time in yellow phase on a Golden Banner flower, that had seized a large Chryxus Arctic butterfly (Teller County, Colorado at an elevation of over 8,000 feet). Arctic butterflies never rest with their wings open, so I knew something was up….

The males of Misumena vatia are certifiable wimps compared to their mates. The masculine gender measures a mere 2.5-4 millimeters at maturity. He is skinny and leggy compared to the voluptuous female, and he has an entirely different color pattern. Not strong enough to secure large meals, he may even settle for eating flower pollen. He matures faster than the female, and as an adult will wander constantly in search of prospective mates.

Mated females eventually produce an egg sac that is usually wrapped in a folded leaf. She guards her brood religiously and will not feed until the spiderlings emerge and disperse. Note the gaunt appearance of the female below, standing guard over her bundle of eggs. The “pleats” on her abdomen reflect the elastic nature of her exoskeleton.

Misumena vatia is a member of the crab spider family Thomisidae; it is a common and widespread species ranging across the entire northern hemisphere including North America, Eurasia, and northern Africa. Female spiders may be yellow or white, with or without rosy stripes on their flanks. It takes a sharp eye to spot them, but I can just about guarantee you have some in your neighborhood somewhere.

Want to know more? Almost every aspect of the natural history of this species has been studied in detail, a fact reflected in the numerous scientific papers generated over the decades. An entire book has even been written about it: Predator Upon a Flower: Life History and Fitness in a Crab Spider, by Douglass Morse (Harvard University Press, 2007). You will also find a more succinct yet still captivating summary at, courtesy of Mandy Howe’s diligent research.

Friday, June 8, 2012

Coming Soon: National Moth Week

Moths suffer from a lot of stereotypes: They eat clothing and infest grains. They are dull and drab. Their caterpillars are garden and crop pests. Only a handful of moths fit those categories, but still people persist in breaking out the pesticides and deploying the bug-zappers.

Ilia Underwing and friends, Cape Cod, Massachusetts

Enter National Moth Week, coming up July 23-29, 2012. Events around the United States are being planned to erase the myths and preconceived notions anyone might have about these nocturnal insects. The concept is the brainchild of David Moskowitz and Liti Haramaty who have been holding public “moth night” events on behalf of the Friends of the East Brunswick (New Jersey) Environmental Commission since 2005. The programs have become quite popular, drawing from thirty to fifty people, and countless moths, to each gathering.

Southern Emerald Moth, Hemingway, South Carolina

Moskowitz and Haramaty, after watching the growth in popularity of the “Moth and Moth-watching” Facebook page, decided to raise the bar in 2011, planning a national week devoted to nightshift Lepidoptera. Currently, events are planned in many of the Lower 48 states and Hawaii, but the idea has also caught fire in Mexico, Europe, even India. Not all of the events are public, unfortunately, but many are. All are designed to collect data to improve our understanding of the distribution of moth species and assess the population levels of vulnerable species.

Western Polyphemus Moth, Chiricahua Mountains, Arizona

As you can see from the images here, moths can be as colorful as butterflies, and even more diverse. Simply turning on your porch light can be enough to attract some truly spectacular sphinx moths, giant silkmoths, tiger moths, inchworm moths, and owlet moths. Even urban areas can have a large number of species. Hot, humid nights with a new moon are best, but really any night will have moth activity to one degree or another.

Large Laceborder, South Deerfield, Massachusetts

I encourage you to find a National Moth Week event in your area by going to the website for Exploring Nighttime Nature and using the event locator page. Better yet, plan your own event and register it with them. We can’t have too many eyes out there.

Achemon Sphinx, Cape Cod, Massachusetts

The website also includes “how-to” instructions for setting up lights, recipes for “sugaring,” and resources to help you identify the moths that you attract. Make sure you remember your camera, too, as their will certainly be some specimens that you’ll want to take a picture of.

Double-toothed Prominent Moth, South Deerfield, Massachusetts

By all means, make an effort to enjoy the outdoors after dark. Look for moths. Look for fireflies. Listen to the katydids, crickets, and whip-poor-wills. Nature puts on its show 24/7 and you miss a lot if you are strictly diurnal. Besides, an evening outside beats the “reality” of summer television by a mile.

Wednesday, June 6, 2012

Wasp Wednesday: Wasps in Love

It seems the theme lately has been insect sex. Seriously, I don’t think I’ve ever seen and photographed so many f*ing “bugs” (literally!) as I have in the past week or two. Wasps have been no exception. It is one of those behaviors for which they tend to sit still for a change. It is also a situation in which you can finally tell the subtle differences between the genders (or not so subtle differences in some cases).

Take the example of the pair of Ammophila thread-waisted wasps shown above. The male is the one on top. The tip of his abdomen is rather blunt, and that he is deploying his, um, “hardware.” The female doesn’t seem to like this very much, though. Notice how her abdomen tapers to a point.

One may logically ask how can mating take place when a female wasp has a stinger. Wouldn’t that hurt the male? How can he get his sperm into such a small, sharp opening? Well, the stinger is not involved in copulation. In the evolution of wasps, the egg-laying organ (ovipositor) has in some cases become modified into a retractable stinger that is now used to paralyze prey, and as a weapon of last resort in self-defense. The female’s sex organs are located near the same opening from which the stinger is thrust, but again, the stinger does not participate in mating activities.

While the sexes are very similar in most kinds of wasps, this is not always the case. Above we have a pair of pollen wasps, Pseudomasaris vespoides, the male attempting to court a female that has her head stuck inside a Penstemon flower. Many male wasps are, shall we say….opportunistic in this way. To his credit, he is petting his potential mate, tapping his “chin” on her back. I wish I had video to demonstrate that, but I don’t. The male is larger than the female, with various hooks and other external anatomical features on his abdomen that help him latch onto his mate. Pseudomasaris males also have much longer antennae than the females, terminating in segments that form a club. She has clubbed antennae, too, just much shorter.

Male wasps may have other body parts modified as well. Males of crabronid wasps in the genus Astata have enormous eyes that meet at the top of their heads: all the better to see passing females as he sits atop an elevated perch. He will also chase off competing males.

Above is a male wasp in the genus Crabro. He has the tibial segment of his front leg modified into a broad shield. Scientists speculate that these plates function in displaying to females and other males, and/or as stimulation to the female during courtship. The shields glisten in the sun, reflecting light brightly and perhaps disclosing the location of the perched male to passing females and competing males. During courtship, the male perches atop the female and covers her eyes with his shields. The shields are translucent and create patterns of light perceived by the female (Low and Wcislo, 1992).

There is much competition among males for available females. This was made graphically clear to me earlier this week when I received an image from someone via, asking me “what behavior is going on here?” The picture showed three male Black and Yellow Mud Daubers, Sceliphron caementarium, stacked on top of a single female. Well, two of the males were stacked on each other, actually.

Females of Eremnophila aureonotata, a thread-waisted wasp, don’t let mating keep them from other activities. The pair shown below is resting, but “engaged” pairs can often be seen flitting from flower to flower just like single wasps. This species is common throughout the eastern U.S. and adjacent southern Canada, so keep a lookout for tandem couples.

In the interest of maintaining my current followers, and in the hopes of recruiting still more, I shall refrain from any comparisons between wasps and Homo sapiens when it comes to sex. I encourage voyeuristic behavior only when it comes to watching insects and arachnids, thank you.

Sources: Bohart, R. M. and A. S. Menke. 1976. Sphecid Wasps of the World: A Generic Revision. Berkeley: University of California Press. 695 pp.
Low, Bobbi S. and William T. Wcislo. 1992. “Male Foretibial Plates and Mating in Crabro cribellifer (Packard) (Hymenoptera: Sphecidae) With a Survey of Expanded Male Forelegs in Apoidea,” Ann. Entomol. Soc. Am. 85(2): 219-223.

Sunday, June 3, 2012

Spider Sunday: Trashline Orb Weavers

When it comes to disposing of garbage, some spiders are neat freaks, while others let leftover meals and other trash accumulate in their webs. Black widows are slobs. At the other end of the spectrum are spiders that recycle their waste, incorporating it into their web architecture to help disguise their own presence. These are the “trashline orb weavers” in the genera Cyclosa (image below) and Allocyclosa.

Don’t blame yourself if you have never seen one of these arachnids. They are quite cryptic, masquerading more or less as bird droppings in color and shape. They spin small, vertical orb webs (Cyclosa is Greek for “to move in a circle,” referring to the spiral nature of the round web), but the snares are relatively small, and the decorations help to make them even more inconspicuous.

There are five species of Cyclosa in America north of Mexico, two of which are common and widespread. C. conica and C. turbinata both occur over the majority of the North American continent. They are difficult to separate, but females of turbinata have a pair of humps on the top of the abdomen. Females of C. conica are a bit larger and lack the bumps. Both species often have a conical or spatulate projection at the rear of the abdomen. This can be very pronounced, or hardly evident.

These are not very large spiders, even as adults. The body length of a mature female C. conica is only 5.3-7.5 millimeters. Males (image below) are only 3.6-4 millimeters.

What makes these spiders truly unique is how they arrange old prey, newly-captured prey, and other debris vertically through the very middle of the web. The spider itself is squarely in the center (hub), but good luck finding it amid the clutter. All of the objects are about the same size and shape as the spider, too. A bird or other visual predator trying to find the spider would be hard-pressed to see it as well.

Look for the webs in open woodlands, and even in shrubs in gardens and yards, well off the ground. I see most of them at or near eye-level, in fact (I am 5’8” for reference).

These spiders reach adulthood in the spring. Mature males do not spin webs, wandering instead in search of potential mates. Mated females then create up to five egg sacs, hiding them on twigs or beneath foliage.

The only species of Allocyclosa found in the U.S. is A. bifurca. It ranges into southern Texas and Florida, building its web most commonly amid prickly pear cacti quite close to the ground. The name bifurca refers to the forked projection at the rear of the abdomen. The adult females are silvery or white in color, and measure 5.1-8.5 millimeters in body length.

Interestingly, you will see females almost exclusively. They arrange trash along the middle of their web, south of the hub where the spider sits. Above her, she arranges a string of egg sacs, each about the same size and color as herself. Can you spot the one in the image immediately below this paragraph?

The rarity of males is perplexing, an unsolved arachnid mystery. The strangely vestigial external genitalia of the females, with no external opening, has lent some weight to the theory that the species is parthenogenic, a scientific term meaning the ability to reproduce without males.

Enjoy searching for these amazing spiders when you are out and about. Also, a wise word for all my gentleman readers: when your spouse asks you to take out the trash, do not take after trashline orb weavers and decorate the den with your disposables. I’m just sayin’….

Sources: Bartlett, Troy, et al. 2004. “Genus Cyclosa - Trashline Orb Weavers,”
Hollenbeck, Jeff. 2007. “Species Allocyclosa bifurca,”
Howell, W. Mike and Ronald L. Jenkins. 2004. Spiders of the Eastern United States: A Photographic Guide. Boston: Pearson Education. 363 pp.