Big Changes Coming Here

I can hardly believe I have been at this for three years and over 300 posts, but that is how it should be. When you enjoy what you are doing, time flies. Time has come to make some changes, though, all for the better I think.

There will be more diversity in the subjects covered here. I will likely be adding “Moth Monday,” “True Bug Tuesday,” and “Fly Day Friday” to the current “Wasp Wednesday” and “Spider Sunday.” “Orthoptera Thursday” is another possibility. You won’t get one of each every week, but you’ll probably get at least two posts each week.

Posts will probably be shorter. I need to expand my audience, and most people do not read online, they scan. They like bullet points. I will do my best to balance thoroughness and storyline with brevity.

I will be debuting a new website. I am privileged to be working with a good friend who is also a website developer to make BugEric dot com a reality, probably sometime in January or February of 2013. Blog posts will likely be moved there, and this site kept as an archive. The new site will offer me far more flexibility in what else I can do, including making products available for sale.

The most important thing I need to do, however, is to promote my name and my site to generate some kind of income. Yes, I could get a “regular job,” but then most of what you are getting would cease to be due to time constraints. Please help me to do this, if you will, through continued donations, recruitment of advertisers, and whatever other avenues you can think of. My expertise is in writing and entomology, not in internet marketing.

I thank you for your continued support through following this blog, and look forward to bringing you an even better product in the future.

Spider Sunday: Nursery Web Spider

If Spiders.us had a top ten list for the spider species we are asked to identify most often, then the nursery web spider, Pisaurina mira, would certainly be on it. This is a large, abundant spider, especially in New England where there are lots of people who see it.

This species also reaches adulthood in the spring, just when people are going out into their yards and gardens. You could not be blamed if you encountered one unexpectedly and decided you’d had enough of this outdoor stuff for the rest of the year. Female Pisaurina mira measure from 12.5-16.5 millimeters in body length, males 10.5-15 millimeters. They are “leggy,” too, so that makes them look larger still (35-45 mm legspan).

Members of the family Pisauridae are collectively known as “nursery web spiders” because of the habit of the female suspending her egg sac in a tangled web just prior to the spiderlings emerging. The mother spider guards both the sac and the spiderlings that hatch, until they molt once more and disperse. This web envelopes a small section of foliage, usually well off the ground in weeds or a shrub.

Pisaurina mira is a hunting spider that otherwise spins no web, or at most minimal “scaffolding” where it sits motionless in ambush on foliage during the day and/or night. They may also hunt actively, sometimes visiting outdoor lights to catch the many insects attracted to the artificial beacons. Despite their small eyes, they are superior at detecting motion, responding quickly to potential prey, or fleeing from perceived danger.

Recognizing this spider is not always easy. Most mature individuals are light brown, beige, or grayish with a broad, dark stripe down the entire length of their body. Immature specimens, and some adults, lack the distinct stripe, however. The spider often rests with the first two pairs of legs held tightly together.

Mating takes place in mid-summer. The male employs a silken “veil” to bind the first and second pairs of legs of his mate whilst they are both suspended from draglines. Each mated female prepares an egg sac, carting the white sphere in her jaws.

© Michelle Lynn St. Sauveur via Bugguide.net

She eventually finds a suitable place to hide her egg sac, such as beneath a folded leaf, and shrouds the whole thing in her nursery web. Her young are the arachnid equivalent of teenagers by autumn, and they seek a snug place to overwinter. Inside cracks and crevices, and beneath loose bark or stones are good places to find them.

Despite their intimidating size, nursery web spiders are not considered to be dangerously venomous to people or pets. To the contrary, they are highly beneficial predators of insect pests in your yard, garden, farm or orchard. The species ranges from southern Ontario and Quebec in Canada to Florida, west to Minnesota, Nebraska, Kansas, Oklahoma, and the Rio Grande Valley of Texas. Look along forest edges in the understory, among grapevines, and on weeds in open fields.

They can be mistaken for wolf spiders at first glance, but are much more likely to be found in the vertical plane rather than on the ground. The eye arrangement differs between the two as well. Pisaurina has all eyes basically the same size.

Sources: Bruce, John A. and James E. Carico. 1988. “Silk use during mating in Pisaurina mira (Walckenaer) (Araneae, Pisauridae),” J. Arachnol. 16: 1-4.
Carico, James E. 1972. “The Nearctic Spider Genus Pisaurina (Pisauridae),” Psyche 79: 295-310.

Wasp Wednesday: Polistes exclamans

Paper wasps in the genus Polistes are more diverse the farther south you go, reaching their zenith in tropical and subtropical climates. Global climate change may be nudging some species farther north, though, so it pays to keep your eyes open. One species that naturally ranges beyond the subtropics is the Common Paper Wasp, or “Guinea Wasp,” Polistes exclamans.

I recommend using the scientific name, as there is no official common English name. This is a widespread insect found from New Jersey south and west to Florida, Indiana, Illinois, Nebraska, Colorado, Arizona, and southern California. It also ranges into Mexico, and has been introduced to Hawaii; and there is one record for Ontario, Canada.

Look for their nests in sheltered places, such as beneath the eaves of homes. They will also nest in trees, but most of the time that I have found nests, they have been attached to some man-made structure. Here is one from beneath an interpretive sign on the hawk watch platform at Cape May Point State Park in New Jersey (October 17, 2010).

Here is another nest on the ceiling of a picnic shelter in the same park (October 3, 2012).

This is a fairly easy species to identify:

• Evenly patterned in red and yellow, usually with black coloration reduced to thin bands on abdomen (occasionally more extensive black markings, especially on top of thorax).
• Antennae banded with red, black, and yellow (most paper wasp species have antennae of one color).
• Size relatively small (forewing length 12-16.5 millimeters).

Like most paper wasps, this species preys on caterpillars that the worker wasps chew up and feed to the larvae in the nest. They feed on a wide variety of moth and butterfly caterpillars, including members of these families: Pieridae (white and sulphur butterflies), Hesperiidae (skippers), Noctuidae (owlet and tiger moths), Notodontidae (prominent moths), Sphingidae (sphinx moths or hawk moths), and Saturniidae (giant silkmoths).

You would think that social wasps in general would not be bothered by predators and parasites given the presence of many stinging adult wasps ready to defend the brood (eggs, larvae, and pupae), but such is not the case. Polistes exclamans can occasionally lose its entire brood to bird predation. The acrobat ant, Crematogaster laeviuscula can also destroy a nest. Partial losses can come from Elasmus polistis, a tiny wasp in the family Eulophidae that infests young paper wasp nests that are defenseless while the foundress is away foraging.

Note males on right have black on thorax and head

Irony of ironies, caterpillars of the pyralid moth Chalcoela iphitalis can take a toll due to their parasitic activities on the wasp larvae. The moths themselves are quite attractive:

This is one of the most studied of social wasps, and the literature cited below is only a fraction of the scholarly works devoted to P. exclamans. Despite this, the known distribution of the species has been clarified mostly through documentation by citizen scientists contributing their specimens and images to universities, museums, and websites like Bugguide.net that are monitored by professional entomologists. Keep up the good work, folks.

Sources: Buck, Matthias, Stephen A. Marshall, and D.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)
Starr, C.K. 1976. “Nest reutilization by Polistes metricus (Hymenoptera: Vespidae) and possible limitation of multiple foundress associations by parasitoids,” J. Kans. Entomol. Soc. 49(1): 142-144.
Strassmann, Joan E. 1981. “Parasitoids, Predators, and Group Size in the Paper Wasp Polistes Exclamans,” Ecology 62(5): 1225-1233.

Spider Sunday: Cave Orbweaver

One of the oddballs of the family Tetragnathidae is the Cave Orbweaver, Meta ovalis. It does not have the exaggerated jaws, long legs, or elongated body typical of most other long-jawed orb weavers. It even spins a vertical orb web, in contrast to the usual horizontal webs made by other tetragnathids.

Meta ovalis has also gone by the name Meta menardi, but it has been determined that M. menardi is a separate species found only in Europe and Asia (to Korea).

This is an average-sized spider for orb weavers, females measuring 8-10 millimeters in body length an males averaging 9.5 millimeters. The species ranges from southeast Canada to Georgia and west to the Mississippi River, especially along the Appalachian Mountains and the Ozark Plateau. It is one of two North American species in the genus, the other being found only in California.

The typical habitat for cave orb weavers is, surprise, surprise, caves, abandoned mines, old wells, basements, and densely-shaded ravines. That is why I found this specimen on the exterior of a building, in broad daylight, in New Hampshire, on October 11, 2009. Since it was not associated with an obvious orb web, my first thought was that it was a sheetweb weaver in the family Linyphiidae, or maybe a cobweb weaver in the family Theridiidae. The spiny legs ruled out cobweb weavers, but I was still mystified.

I collected the specimen and took it to the lab I was using at University of Massachusetts, Amherst, where I took the two images on the table. Fortunately, I had access to good references and was able to eventually identify it correctly.

This is not a true cave inhabitant in the sense that it dwells only in the entrances and twilight zones of caves, and not in the deep recesses. It has obvious eyes, and is fully pigmented. These characteristics classify it as a “troglophile” rather than a troglobite. The webs are usually built from the ceiling of a given location, especially in protected situations (termed “kettles” and “bells” on the ceiling of caves) where dessicating air currents can’t dry them to death. The spider seems to prefer sitting near the edge of the web rather than its center, but frankly, little research and observations have been done on cave orb weavers.

One exception to the dearth of studies is Meghan Rector’s thesis, cited below. She discovered that immature specimens of the cave orb weaver may be distributed slightly deeper in caves, and construct larger webs to increase the potential for the capture of more scarce prey.

Clearly, more work is needed just to determine the geographic range of this species. Fauna of caverns in general is poorly known, and often endemic to a single cave or cave system. Spelunking, anyone?

Sources: Slay, Michael E., Daniel W. Fong, and Mark D. Kottmyer. 2009. “Meta ovalis (Araneae: Tetragnathidae) observed preying on a troglobiotic milliped, Causeyella (Chordeumatida: Trichopetalidae),” Speleobiology Notes 1: 3-5.
Rector, Meghan Anne. 2009. “Foraging in the Cave Environment: The Ecology of the Cave Spider Meta ovalis (Araneae: Tetragnathidae). Master of Science Thesis. 113 pp.
Reeves, Will K., John B. Jensen, and James C. Ozier. 2000. “New faunal and fungal records from caves in Georgia, USA,” J. Cave Karst Stud. 62(3): 169-179.
Yoder, Jay A., Joshua B. Benoit, et al. 2009. “Entomopathogenic fungi carried by the cave orb weaver spider, Meta ovalis (Araneae, Tetragnathidae), with implications for mycoflora transfer to cave crickets,” J. Cave Karst Stud. 71(2): 116-120.