Holiday Gift Guide 2012

At this time of year I like to give a free plug to products that I have found useful myself, or that I believe would be beneficial to my readers and their friends. This year has seen a trio of books that I am proud to sing praises of. I even lent images and text to one of them. Enjoy!

Kollath+Stensaas Publishing continues to turn out highly useful, generously illustrated, and compact regional field guides on subjects seldom treated by major publishing houses. The latest from their presses is Insects of New England & New York, by Tom Murray.

Tom is a prolific photographer of invertebrates and his images here are more than worth the $18.95 retail price of the book. I was profoundly flattered to receive a free copy, but even more astounded to read the acknowledgements:

”When I was first becoming serious about insect photography, Eric Eaton….would regularly visit my website and identify my photos. With Eric’s encouragement I joined www.Bugguide.net in March of 2005.”

Tom should be very proud of what he has done with that “encouragement.” Critics will say that the images of insects identified to species, or even genus, can be misleading to users trying to make their own identifications. This is true, because many species look essentially identical, or are conversely highly variable in color, pattern, and/or size. I would make the counter argument that one goal of a field guide should be to illustrate just how incredibly diverse invertebrates are. Tom and the publishers achieve this in boatloads.

Insects of New England & New York is more comprehensive than most field guides to insects for any region. It should be a standard reference for students of all ages throughout the northeast U.S. and adjacent southern Canada. Still can’t get enough of Tom’s photography? Then please visit his amazing galleries at pbase.com.

Another good friend, who I have yet to meet in person, had her own book come out this year. Seabrooke Leckie, together with David Beadle, produced the Peterson Field Guide to Moths of Northeastern North America (Houghton Mifflin Company).

Seabrooke lives in the wilds of Canada, assuring that any U.S. bias was curbed at least to some degree in the coverage of this book. Those that are familiar with Charles Covell’s A Field Guide to Moths of Eastern North America (Houghton Mifflin Company, 1984), also in the Peterson series, might think this new book to be redundant at best. Not true. Beadle and Leckie cover more species, and illustrate them with images of live specimens. No more pinned specimens with wings spread out. What you see at your porch light is what you will see in this book. Common variations in color and pattern are also shown for those species that vary in their appearance.

This book exceeded my expectations. One thing you might find puzzling, as I did, are the green, red, and orange bars next to the name of each species. Those bars represent “spring,” “summer,” and “fall” respectively. Beneath the bars is a black line that is not readily apparent, but which indicates the flight period for that species. This is explained in the “how to use this book” chapter, but it could have benefitted from a diagram. That is a minor negative, completely overwhelmed by the quality and comprehensiveness of this guide.

Seabrooke is a very gifted writer, and one’s style can be cramped by the constraints imposed by field guides. You owe it to yourself to visit her blog, The Marvelous in Nature, for a dose of her engaging style.

Last, but not least, Kenn and Kimberly Kaufman have another hit in the Kaufman Field Guide series with the Kaufman Field Guide to Nature of New England (Houghton Mifflin Company). Kenn was kind enough to approach me to contribute the terrestrial invertebrate section, both text and a few images, for which I was very grateful. Income never hurts, but it is always a joy to work with him on a new project.

Again, this book far exceeded my expectations, even though I should have known better. Yes, virtually every organism you are likely to encounter, plus geology, weather, and astronomy are covered in this book. From your backyard to the wilderness, it’s in there. Tidepool life, and open ocean fishes are even included. Wait, there’s more! You also get….passages on habitats, sustainability, endangered species, conservation, and invasive species. Now how much would you pay? Ahem. Sorry, I was momentarily channeling infomercials.

I am certain it is not coincidental that all three of these books are focused on New England or the northeast U.S. It makes sense for the publisher, as this is where the majority of the human population lives, recreates, and does business. I look forward to participating in the creation of more regional guides in the future. Breaking our biosphere down into bite-size regions means that you can cover more species.

There you have it, the three books that I think every naturalist should have on their shelves this year. Let me know your opinions, and feel free to make additional suggestions.

Wasp Wednesday: Carrot Wasps

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

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

You can easily identify carrot wasps by the following characters:

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

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

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

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

male

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

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

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

Spider Sunday: Eastern Parson Spider

One of the more common and distinctive members of the family Gnaphosidae is the Eastern Parson Spider, Herpyllus ecclesiasticus. It gets its common name from the black and white color pattern that is reminiscent of the garb worn by old-time clergymen. It also sometimes makes house calls, which can be disconcerting to homeowners.

This species prowls mostly at night, and I find it fairly commonly around buildings, hoping to prey on small insects attracted to outdoor lights. It climbs well, so can be seen well off the ground.

By day, it hides under loose bark, or stones, boards, and other debris on the ground. Specimens that enter homes at night may seek refuge in clothing, shoes, and other objects. The spider may bite if trapped, but the effect of a bite depends mostly on the victim’s immune response. Rarely do symptoms exceed mild inflammation.

This is a mid-size spider, females ranging from 6.5-13 millimeters in body length. Males are 4.5-6.5 millimeters. The spinnerets are prominent in both genders, a characteristic of the family Gnaphosidae. Each spinneret is like a showerhead, with many tiny orifices through which silk is extruded.

The Eastern Parson Spider is widespread everywhere east of the Rocky Mountains, from southern Alberta across to Nova Scotia and south to Texas and Florida. West of the Rockies it is replaced by the Western Parson Spider, Herpyllus propinquus. Look for it in deciduous woodlands.

Mature specimens of this spider can be found year-round, suggesting it is fairly long-lived. Mated females spin an egg sac in autumn. The case is flat, and deposited in a silken retreat where the mother guards it. One egg sac in Connecticut, found under loose bark, contained 130 spiderlings.

Sources and Links: Aitchison, C.W. 1984. “Low-temperature Feeding by Winter-active Spiders,” J. Arachnol. 12: 297-305.
Cox, Shelly. 2011. “Eastern Parson’s Spider,” MObugs
Edwards, Robert L. and Eric H. 1997. “Behavior and Niche Selection by Mailbox Spiders,” J. Arachnol. 25: 20-30
Guarisco, Hank. 2007. “Checklist of Kansas Ground Spiders,” Kansas School Naturalist 55: 16 pp.
Minerva Webworks, LLC. 2012. “Eastern Parson Spider,” Sutton, Massachusetts, suttonmass.org.

Wasp Wednesday: Pepsis grossa

There are many species of “tarantula hawk” wasps in the western U.S., but the largest is Pepsis grossa, formerly known as Pepsis formosa. Interestingly, this insect exhibits both an orange-winged (xanthic) form, and a black-winged (melanic) morph. The two are almost never found together in the same location.

female xanthic form

My experience with P. grossa has been confined to southeast Arizona, but the species ranges from southern California and Nevada to Kansas, Texas, Arkansas, and Missouri. It also occurs throughout the Caribbean islands, Mexico, Central America, and northern South America. The xanthic form is found from Arizona north and east, and also in central Mexico. In southern Ecuador and northwest Peru, there is a “lygarochromic” variation whereby the wings are dark at the base, with a median patch of dark amber, and a pale wingtip.

These are enormous wasps impossible to overlook. Females average a whopping 43 millimeters in body length (30-51 mm). Males are smaller, 24-40 millimeters.

male melanic form

These giants can still be confused with the very similar, but smaller P. mexicana. Males of P. grossa can be distinguished by the fact that they have twelve antennal segments. No other Pepsis species has that number of segments. Females of P. grossa have long, coarse hairs beneath the femur of the front leg, though this feature can be abraded in older, worn specimens.

Females hunt for their tarantula prey mostly in the morning and evening to avoid overheating in the intense summer sun. Flying low over the ground, they may detect the presence of a tarantula burrow by sight or smell. Occupied tarantula burrows have a silk curtain over the entrance by day, and perhaps the wasp is tuned in to chemicals in the silk that indicate a spider is at home. The wasp may also land randomly and scour the soil on foot, flicking her wings and bobbing her antennae feverishly.

Once she does find a burrow with a spider inside, she cuts away the silk curtain and cautiously enters the burrow. Soon, both wasp and spider erupt from the burrow. This eviction behavior is crucial to the wasp’s success in securing her prey. She would have far less room to maneuver inside the spider’s tunnel.

The wasp steps back, grooms herself thoroughly, and then sizes up her adversary. She uses her antennae to entice the spider into raising itself off the ground; or even antagonizes the arachnid into a threat posture whereby the tarantula raises its front legs high, exposing its fangs. The wasp then seizes the second leg and thrusts her stinger between the base of its leg and its sternum. She strikes a nerve center in that location which causes the spider to become paralyzed.

The wasp may feed on fluid from the wound created by her stinger, or groom herself again before commencing the laborious procedure of carrying her prey away.

Tarantula hawks often simply drag their paralyzed burden into back into its old burrow, but on occasion they may dig another burrow and bury the spider there. I am pretty certain I witnessed the very end of this sequence one evening at Tohono Chul Park in northwest Tucson. The female shown below was busy filling a shallow depression by scraping sand into it.

female melanic form

The female lays a single egg on the tarantula and then seals the burrow. The larva that hatches from the egg will then consume the spider. Once finished, the larva will spin a silken cocoon, metamorphose into the pupal stage, and eventually emerge as an adult wasp sometime later.

Look for both male and female tarantula hawks on flowers, especially milkweeds (Asclepias spp.), where they fuel themselves on nectar. During the heat of midday, they will seek shelter amid foliage on trees and shrubs, sometimes gathering by the dozens on one plant. Males, and the odd female, may also spend the night in such aggregations.

Despite their intimidating size, these are rather placid animals unless provoked. An agitated tarantula hawk adopts a threat posture with wings splayed and abdomen curled under. They also secrete a strong, but not unpleasant, odor. Take heed! Stings from Pepsis are not life-threatening unless you are prone to allergies, but the pain is incredible. According to Justin Schmidt, you are in agony for about three minutes, and then it is pretty much over (the pain). Actual results may vary, so I am not volunteering to experiment any time soon. Neither should you.

Sources: Alcock, John. 2000. “The Tarantula Hawk Wasp’s Potent Sting Stuns and Kills the Much Larger Tarantula,” Arizona Highways, 76(10): 40-41.
Hurd, Paul David, Jr. 1952. “Revision of the Nearctic Species of the Pompilid Genus Pepsis (Hymenoptera, Pompilidae),” Bull. Am. Mus. Nat. Hist. 98(4): 261-334.
Punzo, Fred. 2007. “Interspecific Variation in Hunting Behavior of Pepsis grossa (Fabricius) and Pepsis thisbe Lucas (Hymenoptera: Pompilidae): A Field Study,” J. Hym. Res. 16(2): 297-310.
Schmidt, Justin O. 2004. “Venom and the Good Life in Tarantula Hawks (Hymenoptera: Pompilidae): How to Eat, Not be Eaten, and Live Long,” J. Kans. Entomol. Soc. 77(4): 402-413.
Vardy, C.R. 2002. “The New World tarantula-hawk wasp genus Pepsis Fabricius (Hymenoptera: Pompilidae) Part 2. The P. grossa- to P. deaurata-groups,” Zool. Verh. 337: 1-134.