Tag Archives: yellow

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.

Golden-backed snipe fly

Here’s a male golden-backed snipe fly (Chrysopilus thoracicus). The species is strangely understudied. For example, the adults don’t seem to feed, or at least do so very rarely or in complete privacy. I’ve read about them eating aphids, but that’s secondhand at best. The family (Rhagionidae) is full of predaceous members, so it’s certainly possible, but it’s still odd that we don’t really know for sure, and there should be at least a single photograph of them eating something. I wish somebody would PCR their gut contents to settle the issue. Not much is known about the larvae (image), either, other than that they can mature in rotting logs (Johnson 1912). 

Colin Purrington Photography: Insects &emdash; Male Chrysopilus thoracicus on leaf

I’ve photographed this insect twice before. One was floating on top of water, the other was sporting a severely dented eye. They are easy to photograph because they refuse to budge even when the lens gets within centimeters.

 Colin Purrington Photography: Insects &emdash; Golden-backed snipe fly (Chrysopilus thoracicus)

Colin Purrington Photography: Insects &emdash; Golden-backed snipe fly (Chrysopilus thoracicus) with dented eye

Snipe flies (Rhagionidae) are so named because their unfurled probosces resemble snipes (long-beaked birds in the Scolopacidae). Not everyone buys that naming explanation, though. Some insist it’s because of their agile, predaceous habit (i.e., they are good at sniping).

Apple oak gall

Apple oak gall (Amphibolips confluenta or Amphibolips quercusinanis), backlit to show leaf-like venation. Second photograph is a cross section showing where the wasp larva develops. I’d love to know what the spotting does, if anything.

Colin Purrington Photography: Insects &emdash; Backlit oak apple gall (Amphibolips sp.)

Colin Purrington Photography: Insects &emdash; Backlit cross section of an apple oak gall (Amphibolips sp.)

Cynipid wasps love oaks for some reason — over 3/4 of the 1300 species use Quercus as host. People argue about why that’s the case (e.g., Ronquist et al. 2015). Even Alfred Kinsey the sexologist weighed in, back in the days when he was obsessed with gall wasps.