Spider Sunday: Spiders 'R' Us

Yesterday, the people who brought you SpiderIdentification.org launched literally a “brand” new website, Spiders.us. The new website will have an expanded range of more traditional content, not the interactive forum of its predecessor. Not to worry, you can still post “mystery spiders” to the Facebook page for SpiderIdentification.

Spiders.us is dedicated to being your headquarters for everything “spider” in the United States and Canada. The aim is to be accurate above all else, for there exists so much misinformation, contradictory information, and downright myth, superstition and urban legend that it is no wonder so many people are fearful of spiders. We empathize and promise to put the squeamish and scared at ease as best we can.

We will also defend spiders for the important roles they play in nature, pest control, medicine, engineering and other economic and cultural realms. Here you will find:

• Help in identifying the “mystery spider,” or even its web, in your home, office, yard, or garden.
• Help in avoiding and preventing spider bites.
• The latest news on spiders from the scientific community.
• Educational resources from online articles to scientific papers.
• Articles on the positive impacts of spiders on human culture.

We also look forward to hearing from you about how we can make this website more user-friendly and comprehensive. While we see our audience as people with little or no prior knowledge of the arachnid world, you will also find material that is more sophisticated, suitable for naturalists, librarians, teachers, and even scholars.

I am personally looking forward to this new venture, creating content for the site and learning new things myself along the way. Won’t you join me?

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Wasp Wednesday: Passaloecus

I am still learning the very basics of taking images of insects, like using a flash even when it doesn’t look like I need to. Therefore, I have only one respectable image of a live specimen of one of my favorite wasps, in the genus Passaloecus. They are predators of aphids, but are themselves pretty small, averaging 6-8 millimeters in body length.

Besides carting aphids back to their nests as food for their larval offspring, the female wasps feed on “honeydew,” the sweet liquid waste product secreted by aphids in copious amounts. Wasps of all kinds eagerly lap up the sticky fluid from the surface of leaves. That is how I was able to get the image above, on the leaf of a young aspen tree at the Cheyenne Mountain Zoo in Colorado Springs on July 13, 2011.

The genus Passaloecus, pronounced Pass-uh-LEE-kus, is in the wasp family Crabronidae, subfamily Pemphredoninae. There are approximately sixteen species of Passaloecus in North America, collectively found across the entire continent. While they are small and relatively non-descript black insects, I find I can recognize them fairly easily by their white or ivory jaws.

These are solitary wasps that you can actively attract to your yard by providing artificial nests for them. They nest in pre-existing beetle borings, and/or hollow stems and twigs, and vacant galls which they partition into a linear series of cells. As their habitat gets converted to subdivisions and dead, standing trees are preemptively felled to avoid lawsuits, these wasps face a real estate shortage. Simply drilling holes about 3/16th of an inch in diameter and to a depth of four inches or so into a wooden block, and placing the block in a sheltered situation well off the ground, you can provide housing for these beneficial bugs.

The nest tunnel is divided into cells with partitions usually made of plant or tree resin. Each cell is provisioned with a number of paralyzed or dead aphids (from six to over sixty according to the literature) and an egg laid on one of those victims. The female wasp may sting an aphid victim, or crush it to death in her jaws, before taking it back to the nest.

Nests of Passaloecus ithacae may contain six to twelve cells each (Krombein, 1967). There are two generations annually, at least in Erie County, New York. Nests of this and other species of Passaloecus are subject to parasitism from the cuckoo wasp Omalus aeneus and the ichneumon wasps Poemenia albipes and P. americana.

We tend to think of lady beetles and lacewings as the prime predators impacting aphid populations, but Passaloecus and related genera of wasps clearly have an effect as well. Perhaps we need to re-think our assumptions and expand our natural allies in pest control to include wasps (Corbet & Backhouse, 1975).

Sources: Bohart, R. M. and A. S. Menke. 1976. Sphecid Wasps of the World. Berkeley: University of California Press. 695 pp.
Corbet, Sarah A. and M. Backhouse. 1975. “Aphid-hunting wasps: a field study of Passaloecus,” Trans R Entomol Soc Lond 127(1): 11-30.
Fricke, J. M. 1993. “Aphid prey of Passaloecus cuspidatus (Hymenoptera: Sphecidae),” Gt Lakes Entomol 26(1): 31-34.
Krombein, Karl V. 1967. Trap-Nesting Wasps and Bees: Life Histories, Nests and Associates. Washington, DC: Smithsonian Press. 496 pp.
http://researcharchive.calacademy.org/research/entomology/Entomology_Resources/Hymenoptera/sphecidae/Genera_and_species_pdf/Passaloecus.pdf

Spider Sunday: Mystery Solved

Note: This post originally appeared on Sunday, November 6, but I pulled it in the wake of what turned out to be mostly a misunderstanding. After careful deliberation I am resurrecting the story. I think it is instructional in terms of how problems like this are resolved. I normally do not charge a fee for a simple identification, but this was an exceptional case involving a corporation with much to lose without intervention.

This past Wednesday, November 2, I was presented with a unique opportunity to solve an arthropod mystery for a corporate client. A friend in state government sent me a message on Facebook that morning asking myself and another colleague who we would recommend for identifying spider specimens for a company in an Atlantic coast state. I wrote back that the inquiring party could send specimens to me, but that I would charge a modest fee for my expertise. My government friend thought that seemed reasonable and put me in touch with the company representative.

Later that morning I received a phone call from the Director of Regulatory Compliance for the company suffering from a “spider infestation” in a recent shipment of merchandise from overseas. He decided he would overnight specimens to me for examination.

The next morning, the company rep e-mailed me with two images of the spiders in question. I was pleasantly surprised by the detail in those pictures:

It was clear to me from the images that the spiders were some kind of “cellar spider” in the family Pholcidae, but I could not conclude what genus, let alone species, without putting actual specimens under a microscope. At least I could tell him that the arachnids were nothing considered to be dangerously venomous according to current scientific understanding. Time was of the essence and I hoped that my reply to his e-mail might be sufficient.

I received a message from FedEx with a tracking number for the package, and discovered that I would not receive the shipment until Friday morning. Meanwhile, I did not hear back from my company contact.

Indeed, I heard a knock on my door around 10:00 AM on October 4, and there was the FedEx delivery person with a box for me. Interestingly, he seemed quite eager to part with the parcel….

I was amused to find that inside this rather large box was a great quantity of bubble-wrap and a teeny-tiny little vial with a single spider inside. I believe the spider was actually alive when it was packed up, though it was deceased when it arrived. It was still limber and in no way compromised in its anatomical integrity.

I gently placed the creature into a glass petri dish and under my microscope. It was immediately apparent that I had an immature specimen, which would make identification more difficult than it would be with an adult specimen. Still, I broke out my “bible,” the Spiders of North America: an identification manual, turning to the family Pholcidae. The key to genera was sufficient enough for me to conclude that the spider belonged to the genus Pholcus: eight eyes, not six; no pit or groove in the carapace.

Up until recently, it would have been safe to extrapolate to the species P. phalangioides, the “Long-bodied Cellar Spider,” a very abundant and widespread species. However, I learned from my arachnologist colleague that another species of Pholcus, P. manueli, is expanding its range in the United States. Further, there are evidently a number of undescribed species in the genus.

I called the company representative today with the verified identification.

Wasp Wednesday: Pollen Wasp

Today, as I write this, there is snow on the ground and the temperature is somewhere in the 20s (Fahrenheit). You can’t blame me for harkening back to July 11 when it was warm and I was hiking with friends in Emerald Valley near Cheyenne Mountain here in the Front Range of Colorado. One of the insects that excited me the most that day was Pseudomasaris vespoides, one of the “pollen wasps” that stands in such stark contrast to its social and predatory relatives.

Pollen wasps comprise the subfamily Masarinae in the family Vespidae. They collectively occur across the globe, in western North America, southwestern South America, northern and southern Africa, southern Europe, central Asia, and most of Australia, absent from tropical regions. Only the genus Pseudomasaris exists in North America, with 14 species.

These are solitary wasps, each female constructing her own mud nest and provisioning each cell with pollen and nectar, more like a bee than a wasp. The wasps visit Penstemon, or Phacelia and Eriodyction almost exclusively, with additional records for some other flora genera. This pollination relationship is termed “oligolectic” when an insect is obliged to harvest pollen from such a limited diversity of flowers.

The female Pseudomasaris vespoides that I observed on that July day were all visiting Penstemon blossoms. I did not see any males, but populations of this wasp peak in late June with males emerging before females, so their absence later in the year would not be peculiar. Males, easily identified by their very long, clubbed antennae, patrol patches of flowers likely to be visited by females. This is in contrast to the hilltopping behavior of P. maculifrons that I addressed in a previous post.

Females fashion earthen nests comprised of several cells. While most Pseudomasaris adhere their nests beneath stones or other sheltered situations, P. vespoides tends to attach its nests to twigs out in the open, like the one shown below, from Catalina State Park in southern Arizona. The nests may be parasitized by the cuckoo wasp Chrysurissa densa.

P. vespoides is a relatively widespread species, occurring from Washington state south to California, Arizona, and New Mexico, east to Wyoming, Nebraska, and South Dakota. Females and males are about the size of your average yellowjacket wasp and can easily be mistaken for their social cousins. Pollen wasps, however, do not have the longitudinal fold that other vespid wasps display when the insects are at rest. Pollen wasps also have clubbed antennae, whereas other vespids do not.

Sources: Gess, Sarah K. 1996. The Pollen Wasps: Ecology and Natural History of the Masarinae. Cambridge, Massachusetts: Harvard University Press. 340 pp.
Richards, O. W. 1963. “The Species of Pseudomasaris Ashmead (Hymenoptera, Masaridae). University of California Publications in Entomology 27(4): 283-310.