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Trypoxylon - Trypoxylon politum - female

Trypoxylon - Trypoxylon politum - Female
Brookside Gardens, Montgomery County, Maryland, USA
September 13, 2015
Size: ~28mm
Based on this paper (1) and in decreasing order of confidence, Trypoxylon subgenus Trypargilum (“Fore wing with costa not produced beyond radial cell”, “abdominal sternites 2 to 3, usually 2 to 5, bare, with pubescence only at bases of paired bristle”); T. politum (“First abdominal tergite with lateral margins parallel for only a short distance then widening rather abruptly: apex nearly three times as wide as narrowest portion”, “Pubescence of head and thorax black” [they look black to me, at least relative to the guide’s photos of T. lactitarse]

From what features I can see that are used in this paper’s key for subgenus Trypargilum (2), it seems to belong to the “Albitarse group” (“black wasps with yellow white to pale yellow on hindtarsi”). Using the key for females of that group (2) also seems to point to T. politum (Couplet 7: “Gastral segment I robust, strongly flaring laterally from near anterior end”, “hindtibia with spines on anterodorsal surface near base” [barely visible in photo 4], “head width = 4.0-5.9mm” [~4.6mm in this individual], “forewing length 12.0-18.7mm” [~14.7mm in this individual]. Couplet 8: “hindtarsomere V usually yellow white to light brown” (vs. “dark brown to black”). Couplet 9: “Southeastern Ontario and Eastern U.S., head width = 4.6-5.1mm, forewing length = 14.8-16.2mm” (vs. a larger Mexican species, T. giganteum))

After all of that, I’d very much appreciate it if someone with more expertise would confirm or correct that ID. Thanks in advance for the help

(sizes estimated from the photo and the reproduction ratio)

Images of this individual: tag all
Trypoxylon - Trypoxylon politum - female Trypoxylon - Trypoxylon politum - female Trypoxylon - Trypoxylon politum - female Trypoxylon - Trypoxylon politum - female


Amazing photos!
In person, I've only ever seen their pipe-organ nests, also at this location.

This is the only one of these wasps I've seen up close. Brookside is a pretty amazing place for finding insects
I saw that you're starting to submit some of your Maryland photos to the Maryland Biodiversity project. That will be a great addition to the site

I agree, Brookside is an amaz
I agree, Brookside is an amazing place, especially when you start to wander into the outlying forests. I've tend to prefer the C&O Canal Park--have you ever noticed any qualitative differences in findings between the two?

Actually, I haven't been submitting to the MD biodiversity project myself-- it's just that the creative commons permissions for my BugGuide account have allowed somebody to copy many of my images over.

they are different
although I can't say that I can quantify any difference in the range of species between them. Part of the canal are much better for dragonflies, Brookside might be better for pollinators. I tend to go to Brookside more often because it's easier to get to – and you don't run the risk of being mowed down by some hardcore bicycle racer in training :-)

Moved from ID Request.

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