End band net-wing beetle (Calopteron terminale)

This week I finally decided to teach myself how to identify Calopteron terminale (end band net-wing beetle), and the characteristics aren’t as bad as I thought. I made a visual to help in case others might find it useful:

Identifying End band net-wing (Calopteron terminale)

The easiest diagnostic feature is the transverse depression (dip), shown with a red line in photograph above. I think when I first noticed this depression in the wild I foolishly assumed it was a deformation that certain beetles got from being wedged into a pupal cases that were a tad too small for their bellies. But no, it’s a real, unique thing for this species. And no, I have know idea why they have it.

Below is another of my C. terminale photographs. In this one you can see that there’s a second, slight depression just anterior to the transverse band. For this reason many keys refer to an “undulation” along elytra rather than just a single depression. Here is one on Instagram that really shows the undulation. But sometimes the anterior one is hard to see.

Colin Purrington Photography: Insects &emdash; End band net-wing (Calopteron terminale)

Even the distal depression is sometimes hard to see with dorsal photographs, so in those cases use the uniformity in discal costae (ridge, vein) heights to make the ID. Excluding the edge vein there are four (4) ridges that are “elevated” to the same amount. Both C. reticulatum and C. discrepans (the other two members of the genus in the United States) have alternating ridge heights. The ridges are filled with poisonous hemolymph, by the way, so don’t poke them.

In addition to the above diagnostic features, many keys say that C. terminale has a “distinct blue tinge”. Other species in the genus sometimes have a blue tinge but I’ve only noticed a distinct blue tinge on C. terminale. 

For more information on identification, here are links to C. terminaleC. reticulatum and C. discrepans on BugGuide. If you’re on iNaturalist, here they are again: C. terminaleC. reticulatum and C. discrepansThere are many more (100+) species in the genus, and most of them are in South America, Central America, and Mexico. I’m not aware of a current guide to these other species but here’s an 1886 one for Central America.

If you encounter a mating pile of any of these insects, please take a lot of photographs and examine the abdomens of females for droplets of hemolymph. There are reports (Burke 1976) that males feed on this hemolymph. So if you get a good pic, send me a URL of the image so I can link to you.

For more natural history, start with these publications:

Burke, H.R. 1976. Observations on the adult behavior of the Lycid beetle Calopteron terminale (Coleoptera: Lycidae). Entomological News 87:229-232. 

McCabe, T.L., and L.M. Johnson. 1979. Larva of Calopteron terminale (Say) with additional notes on adult behavior (Coleoptera: Lycidae). Journal of the New York Entomological Society 87:283-288.

Augochlora pura foraging for pollen on maize

Last week I found hundreds of pure green Augochlora (Augochlora pura) foraging for pollen on Zea mays at Stroud Preserve in West Chester, Pennsylvania. Here’s my favorite capture, which shows a bee cutting open an anther with her mandibles.

Augochlora pura foraging for pollen on corn (Zea mays)

I was a tad surprised to see a wind-pollinated plant so mobbed with bees, but a later search of the internet suggested I shouldn’t have been. Even honey bees forage on corn, though the pollen is apparently not as desirable as other sources (e.g., Höcherl et al. 2011). This is also the reason why spraying a cornfield with insecticides can easily cause problems for any bees (and pollen wasps) that collect pollen.

This next photographs shows a better view of the scopa (modified hairs that hold the electrostatically-charged pollen) on the legs and abdomen. It also shows off how incredibly large corn pollen is (perhaps 85 microns, per some estimates, which is huge). Wind-pollinated plants with large pollen are odd.

Augochlora pura scopa with corn pollen

The final photograph shows some pollen grains set in motion by the foraging bee. The odd look (line segments with bright dot in middle) are presumably caused by the flash freezing the fast-moving grains only in the middle of the exposure (1/200 of a second). I’m not exactly sure why the grains are bright. It could be because they are strongly backlit by sun, but it could be something related to how pollen grain exines bend light (they can cause a pollen corona on allergy-alert days). Someday it might be fun to get a rear-curtain flash configured to better capture such motion.

Pure Green Augochlora (Augochlora pura) collecting pollen from corn

Oak leaf-rolling weevil (Homoeolabus analis)

If you’ve been to Florida and stared at any of the live oaks there, you’ve probably noticed the tiny, burrito-shaped structures on many of these leaves. If you haven’t seen them, you might have heard them — they accumulate under oak trees in sufficient numbers that you’ll hear crunching as you walk over them.

These structures are made by the oak leaf-rolling weevils in the subfamily Attelabinae (the “leaf rolling weevils”, appropriately) and they are called nidi (Latin for “nest” or “place where egg is placed”). Several species ninidify (yes, it’s a verb) oak but perhaps the most common species is Homoeolabus analis. I caught a female in the act:

Colin Purrington Photography: Insects &emdash; Oak leaf-rolling weevil (Homoeolabus analis) nidifying a live oak leaf.

This shows her fairly well along in the process but I really wish I could show you a video of her technique, which is amazing. Before this stage she’ll first survey the leaf compulsively, scissor the leaf in half at the midrib, then use mandibles and legs to feverishly roll it into a burrito. Midway through the nidification she’ll deposit an egg (sometimes two) and then, I gather, will guard the nidus from parasitic wasps while it hardens up a bit. She’s also guarding against intrusion by the the thief weevil (Pterocolus ovatus), a blueberry-like attelabid that sneaks into fresh nidi and eats the eggs. But that’s not all. Female thief weevils will leave their own egg inside the nidus and this theft of home is the source of their common name.

Here’s a male, by the way (you can tell because he has a longer neck):

On that note, here’s an egg I found inside one of the nidi. I think it’s Homoeolabus analis but it could be Pterocolus ovatus.

I opened up several dozen of these nidi and found all sorts of drama. Several had some sort of orange cecidomyiid larvae (more pics) in the middle layers of the nidi:

And found plenty of eggs that were definitely not weevil eggs but that are not photogenic enough to post. Suffice it to say that there are many parasitic wasps that have been known to attack this species. If I lived in Florida I’d have hundreds of these in vials just so I could watch the emergers. Better than television.

As a side note, if you have a beetle that looks like Homoeolabus analis, it easily could be Synolabus nigripes, a member of the Attelabinae that also has red, punctate elytra and pronotum; black legs with swollen femora; and long rostrum that is largely though variably black. And ranges overlap (see maps here and here). Below are some ways to tell them apart that I collected from a variety of sources. Many involve knowing which sex an individual is, but luckily males have longer necks. And if an individual is caught nidifying a leaf, it’s a female.

Homoeolabus analis

  • sides of neck parallel, not wider near pronotum (from Boris Büche)
  • males: distance between pronotum and eyes equal to length of rostrum (example)
  • males: pair of spines/projections on the submentum (p. 175 in The Insects and Arachnids of Canada; p. 707 in American Beetles); need a microscope
  • females: straight tibiae (see 2nd pic near top of this post)
  • on, eating, or nidifying Quercus spp.
  • black parts have a blue tinge (see above pic) (LeConte 1876, page 10); this characteristic seems ignored in all later descriptions … but I think it should be featured

Synolabus nigripes

  • width of neck behind eyes greater than width at tip of neck (from Boris Büche)
  • males: distance between pronotum and eyes less than length of rostrum (to me, they evoke the Spy vs Spy comic book characters from Mad Magazine)
  • males: large spine(s) on front femora (example)
  • females: “ventral rostral apex in lateral view with median conical prominence” (American Beetles, p. 707); need a microscope
  • on, eating, or nidifying Rhus spp.; usually sumac, sometimes poison ivy
  • no bluish tinge on black parts (Evans p. 464)

If you still need help IDing, submit a photograph to either iNaturalist (I’m @colinpurrington if you want to tag me in your observation) or BugGuide. Here are Homoeolabus analis observations on iNaturalist.

If you want more information on Homoeolabus analis or the parasites that attack it, here’s a great overview by Donald W. Hall and Lyle J. Buss (both at the University of Florida). And here’s a post by Charley Eiseman with pics and natural history of yet another (but not all-red) oak leaf-rolling weevil, Attelabus bipustulatus. If you want to see some nidifying, there are YouTube videos of various Attelabidae.