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Yellowjacket - Vespula sp. - Dolichovespula arenaria - male

Yellowjacket - Vespula sp. - Dolichovespula arenaria - Male
Central Park, New York City, New York, USA
July 30, 2006
Last Yellowjacket submission I had wrong genus. Maybe this time too.

Images of this individual: tag all
Yellowjacket - Vespula sp. - Dolichovespula arenaria - male Yellowjacket - Vespula sp. - Dolichovespula arenaria - male Yellowjacket - Vespula sp. - Dolichovespula arenaria - male

Strange Dangling Tarsal Structures?
The tarsi of this wasp appear to have relatively long, branched, thread-like structures with tiny black, bead-like internodes. (They're best seen in the last of the set of three images.)

I've never seen anything like this! Anyone have insights on these bizarre structures?

Those structures
are pollinia (numerous pollen grains held together by a waxy coating). Milkweed flowers have "pinch traps," which are specialized structures for effecting pollination. Bees or other pollinators get their legs caught in the trap, and in the process of pulling free, they withdraw a mass of pollen known as a pollinium. Unfortunately, the pollinators often lose their legs (or parts thereof) in the process.

Ahh, good point!
Thanks Karl, for making the pollinarium connection here! I should have thought of that, being that I come to insects from a botanical background...and am especially fond of (and fascinated by) milkweeds. At any rate, it helps me appreciate your observation :-)

When I initially made my comment above, I wasn't a BG editor and couldn't see the images here at full-size. But now, at full-size, I can definitely make out the many pairs of waxy, translucent yellow ("insect-wing" shaped) pollinia, as well as the associated tiny black ("seed-like") corpuscula (see this figure for terminology). I think I can count at least 50 pollinaria on this wasps legs! As you mentioned, I can imagine this could cause problems for the pollinator when the pollinia get caught in the receiving slit of another milkweed flower...and the insect attempts to fly "up-and-off"! (And perhaps you also had in mind the possibility of an insect's leg getting caught in the slit...and injured...even without the presence of an attached pollinarium.)

For those interested in learning more details about the fascinating insect pollination mechanisms of milkweeds, and their associated floral structures, take a look at the nice article from the "American Bee Journal" available here as a PDF. It's 4 pages long...nicely illustrated and well-written. Another very good discussion of the topic is available as a PDF in the (more academically oriented) paper here.

Neat stuff!! Thanks again, Karl, for setting me on the right track here.

Same species, same gender (Dolichovespula arenaria, male)
This time, an important feature is quite visible, i.e the pronotal carina. This latter is "materialized" by the faint vertical yellow stripe behind the head.
Nice shots, showing that yellowjacket males too can be pollinators of milkweed flowers.