Graphopsocus cruciatus

Martha O'Kennon

Over the past few years, I've become fascinated with the tiny creatures, almost invisible to the eye, called barklice. They frequent my workshop's blue steel siding most months of the year, with the exception of January and February in South Central Lower Michigan. Finally in 2018, with the purchase of a new camera with a nice Macro lens, I started to get pictures of not only the adult barklouse, but also their really nearly invisible nymphs. Here's a sample of the ones I've documented.

One of the first ones I found possible to distinguish in its adult form with the naked eye is Graphopsocus cruciatus. This is a very attractive insect and probably one of the commonest barklice. On October 12 and 24 I found two females with clutches of eggs.

In the first week of October, 2019, we had begun to see these older nymphs (based on their wing-length). I still wonder if the difference in the abdomial color is related to gender, er, sex. Both of the nymphs in picture 1 already have little wing buds. Some nymphs don't have the thoracic spots and may be those of Valenzuela flavidus, which show up as adults about the same time as G. cruciatus. On the other hand, one of the things I want to find out is whether the spots can develop with age. Third looks more like G. cruciatus. Both of these last are of a more advanced instar, as you can see from the wing length. I think we are following at least two batches of nymphs. I'm not sure when the eggs from the last row of pictures hatched and started their cycle. All of these nymphs were born before the eggs above were laid.

Picture 1 shows two nymphs on October 9. Note that one has longer wings than the other. One of them has just emerged from the strange skin that always appears when a new nymph shows up. In picture 2, we see a nymph emerging from one of these skins. And in picture 3, I THINK what we are seeing is an adult emerging from what will be left as one of those skins.

In pictures 1 and 2, taken on October 23 and 29, resp., we see a couple of somewhat older nymphs - their wings are longer and wider - They will be adults in not too much longer.


I REALLY wanted to see if we couldn't begin on another batch in 2020. I saw NOTHING to think was a Barklouse adult or nymph until April 2, when a picture of a leafhopper (Erythridula abolla) was seen on cropping to harbor a really tiny barklouse nymph. It didn't have any wing development, so I'm figuring that it is one of the earliest forms the nymphs take. So I started really looking for other signs of nymph life but didn't see anything until a very strange configuration appeared (above my eyesight, so the pictures are less than optimal) on February 11. Picture 3 shows that strange scene, what looked like an ant's rear end protruding from some kind of straw-like web and just outside that "web", one nymph on the left and what looks like another on the bottom of the picture. Could this be some kind of nest?

No more sightings until May 4 and 6, 2020, when I spotted one and then two nymphs near what looked like a pile of hatched eggs. Later, on May 7, I was able to locate that view, which was at about the same relative height and appeared like a tiny film of whitish dust to my view. On the screen it turned out to look very much like a field of hatched eggs.

The nymphs on that east wall have steadily grown. Picture 1 shows one on May 4 with the skin it has abandoned. Pictures 2 and 3 show two nymphs each on May 11. In each picture, one clearly is advanced a bit since it has little wing buds. If the other has any wing buds, they are certainly minimal!

Last year (2019) I'd seen quite a lot of barklouse nymphs and adults on the North side of the Shop, especially on the closest panel to the east corner. But this year I've been looking since the ones on the East side started up, and seeing nothing. The ones on the East side were getting easier to see as they grew longer, but there were NO easy-to-see ones on the North side, even on panel 1. But on May 17, my close looking paid off. Suddenly a little bunch of tiny dots just "looked right", even though they didn't look like the ones on the East face. All of a sudden a hunch paid off and some really tiny nymphs appeared in the picture. But then I couldn't find them again. Then I did - and made a little circle on the wall. When I cropped the picture (picture 2) so that I could really see the little nymphs, it was clear how much younger they were than the ones on the East Wall. They had less color compared to the East nymphs, and were shorter. They also had no wing bud advancement, so they are very young. Picture 3 (and picture 4, its cropping) shows a bunch of little bugs in a line on a corner. You can see up close that they were lots of nymphs. Aside: the difference in color makes me wonder if these might not be nymphs of a different barklouse. We must just wait and watch. This is, after all, one of the loci of V. flavidus nymphs in fall 2019.

The next day, May 18, rained like crazy. When it was safe to go outside, I looked all over the panel on the North Wall where I'd seen all those little nymphs, but they seemed to have been washed away. The Wall was so wet! Finally - there was ONE nymph.

The next day (May 19) I finally saw, near a big bolt holding the siding together, a little enclave of three little nymphs clearly like the ones from May 17.

By the way, on May 21, back over on the East Panel the nymphs are getting still longer wings. I was especially surprised to see on May 22 the third nymph. It is particularly long and with good wing development. It also seems to have just emerged from the skin at top. Scott- it almost looks as if it has an extended thorax. What do you think? Maybe it gets stretched out as it moults.

Back to the North Panel. The new babies seem to have been dispersed by the rain. On two panels in particular, 2 and 4, there are fair-sized groups of the babies. First is the group from May 21. The next two bunches are from May 22.

On the East Wall, the nymphs continue to grow. In picture 3, taken on May 24, the nymph has the longest wings and biggest eyes yet.

Today, May 24, is one week since spotting the tiny nymphs on the North Wall. They are still very hard to see but I'd say marginally easier than last week. They concentrate an inch or so above the bottom of the Wall. Today we saw groups on panels 1-4. In picture 3, you can see more clearly the longitudinal stripes. My colleague, Scott Shreves, says that he has seen those stripes in nymphs of various species and genera.

May 26. There has been some counter-clockwise rotation of nymphs. Quite a few of the larger nymphs from the East Wall have migrated to the North Wall. In quite a few cases, the migrants seem to be older with longer wings. One thing we can say about the denizens of the East Wall is that their wings ALL have grown - none remain with no wings. First here, on May 25, an easterner on the North Wall sports longish wings. Second, on May 26, one in home position on the East Wall has spun itself a fairly heavy protective web. Third, one of the tiny nymphs from the North Wall has moved to the East Wall. I don't think any of these has wings enough to help them navigate. But I've observed quite a few on the East Wall that move pretty quickly from place to place. So they have the capacity to walk where they like.

Back to the little striped ones on the North Wall. I'm beginning to be able to see them, especially if they are grouped together, which is common. I don't know if they are grouping for protection, but they definitely do group. But actually, they are perceptibly bigger than they were a week ago. First, a nicely developed one from somewhere on the North Side. Second, a little group from Panel 4 on the North Side. Third, some of the nymphs from Panel 1.

I finally was able (May 27, about 9:30 am) to catch one of the tiny nymphs in action on the North Wall (panel 1). You can see that although they are very small, they are capable of running around and it seems that this one has found some edibles. They also don't seem to like bright light. Maybe this is why they always seem to be found in the shade at the edge of a panel.

Copyright Martha O'Kennon 2020