Friday, August 17, 2012

Unfinished business

First, unfinished business from my last post, where I reported that we had had an unprecedented two Long-tailed Skippers hanging out in our garden, one with both tails broken off, and one with a perfect set of tails. The new development is, Mitchell Pruitt came by the house to see and photograph them, and the one that appeared had one tail broken off. We thought our perfect-tailed one must have had an accident, but later on the perfect-tailed one reappeared, so what we had been seeing was a third Long-tail. In fact the perfect-tailed and the one-tailed were on the lantana together, and I tried to get what would surely be the only photo ever of two Long-tails together in Arkansas, but they were so flighty I could never quite get them side by side. Here is a picture of the one-tailed by himself,  looking, actually, a little bit beat up.

For new unfinished business, we have been on two quests, which have involved us in some driving, and in much slogging around in the heat, and these quests are ongoing because we haven't quite finished them satisfactorily yet. As I contemplate writing about them here, I begin to realize what a hard job I am going to have to try to make these quests seem (to normal people) worth the effort we are expending.

To begin with, there is a robber fly called Psilocurus nudiusculus. The name might sound intriguing, but the fly doesn't live up to it. It's so tiny it is very difficult to see. And when you do see it, it is frankly rather plain. Well, it is so difficult ever to spot one that we hadn't seen the species for years, and we didn't have any very good photos of it, so I made one of my goals for the year to get some better photos. The species occurs in wetlands on bare, somewhat weed-grown paths along the edge of canals or ponds. I remembered a path where I had seen them before on the edge of a floodway of the St. Francis River a few miles south of Marked Tree in Poinsett County.

We drove there and to our chagrin the first part of the path had been "improved" by Game and Fish. They had dumped tons of gravel (big white sharp-pointed pieces) to make a parking lot for the boat launch there. Farther on, what was left of the path was so overgrown with weeds it did not have the bare patches of ground that the robber flies wanted. We walked the path anyway, but found nothing.

We came back to the parking lot (admittedly, it was a convenient place to park) and stood by our car eating our lunch while we decided what to do next. At that point Cheryl looked down on the gravel and noticed a male P. nudiusculus doing a courtship flight. We spent some time crawling around on our hands and knees under the pickups and boat trailers trying to photograph them, and hoping none of the fishermen would return prematurely. The robbers were so small, and so skitzy, it was very difficult to get them focused in our lenses, and the dark flies against the white gravel were difficult to expose for. We got much better pictures than we had previously had, but I still wasn't satisfied with mine. Here is a not bad photo of Cheryl's, showing a male (even tinier than the female) with its prey, some kind of large red mite.

A couple of days later we went to Big Lake NWR in Mississippi County to visit their Moist Soils Unit. It is one of only two sites in the state where Bronze Coppers sometimes occur, and we wanted to see if there were any around this year. Also there are some grasshopper species that occur around wetlands, and the Reserve is a particularly good place to look for them. When we got there we saw that one of the paths, which had been torn up by last year's flooding, had been rebuilt and covered with new gravel, big white sharp-pointed pieces of gravel. We looked at each other, then walked up the path with our eyes glued to the ground. We had never seen nuduisculus here before, but perhaps that was because we had not strained our eyes looking for them. On this day we immediately found one, but I still didn't get very good pictures. Partly it was because the gravel was cutting into my knees so much I couldn't concentrate on such a delicate thing as focusing on the tiny dots in front of me. Here is a picture Cheryl took of me. You can see the fly on the gravel to get a sense of his size.

We did by the way find a pretty little Bronze Copper, nectaring on the frog fruit beside the path.

We had however this other task we had set ourselves. We took another path along the water, and this one featured numerous Obscure Grasshoppers (though why a strong-flying, bright green and yellow, three-inch-long grasshopper would be called obscure I have no idea). Now, another grasshopper, the Leather-colored Grasshopper, apparently has a green phase that so exactly resembles the Obscure that it is difficult to tell them apart. One way, we read, is that the Obscure has black hind tibiae, and the Leather-colored has brown hind tibiae. Just to make things even trickier, the two species regularly occur together.  So we walked down this path, bright green and yellow grasshoppers flying up at every step and disappearing behind the tall aquatic grass growing just offshore. When they landed in view, we scrutinized them with our binoculars, trying to see the hind tibiae, and when we saw brown rather than black, we tried to photograph them. We did find a few among the predominantly black hind tibiae. Here's one.

I sent a picture to Herschel Raney and said "here's a Leather-colored Grasshopper" and he rather doubted it, and the truth is, so did I. (For a reminder of what an Obscure looks like, here's a photo of one I had on a previous blog.)

What I needed was some absolute mark, not something as iffy as leg color. When you want positive identification of insects, almost always it involves a careful study of male genitalia (we don't like to mention this to non-entomologists). There is a part called the "subgenital plate." The back of this plate is partially split into two flanges. On the Obscure, the split is very deep and "V" shaped; on the Leather-colored it is shallow and "U" shaped. So, we returned to Big Lake, and first of all, I put on heavy knee pads, which allowed me to crawl on the gravel painlessly and concentrate on my focusing. I got a better, an almost satisfactory, picture of a female nudiusculus.

But the females are rather plain, and the males, more interesting looking, kept skittering away from me. So, unfinished business.

I had also brought a net with me, and I now went down to the Obscure path and began catching every male I saw. When I caught them I would check for leg color, and then for the shape of the flanges, take a photograph, and then release them. Here, for example, is how the Obscure males looked. In the first photo you can see the black hind tibiae, and a side view of the two flanges at the very end of the abdomen on the ventral side. In the second picture, taken from below, you can see the V shaped gap between the flanges.

Now, the big question is, what do the brown-legged ones look like from this view? Well, I didn't find a single brown-legged male.  So I guess I'm going back there.

No comments:

Post a Comment