July 24th, 2007
tiny curiosities
This last few weeks, I’ve been fairly busy photographing insects and trying to deal with all of the camera downloading, image sorting, backing up of drives, etc… that is associated with digital images. I see so many things that I’d like to share, but am never quite sure just how interesting these images are to others. Today’s offerings seem a bit on the unusual side – even to me – so I decided they were worth writing about.
Before I say anything more about the top photo, imagine a spot no larger than your thumbnail on the bark of a tree. Yesterday, I noticed such a spot a couple of inches above a tiny patch of lichen on a poplar along one of the trails here at the farm. As I moved in close to investigate, the spot began to move, morphing into a ring, and then moments later, reformed as a dense spot back in its original position. It was then that I realized that I was looking at some type of insects so small that I couldn’t really see what they might be. I shot a few photos and then viewed them on the LCD screen. Whoa! I discovered a herd of tiny creatures with bright yellow stripes around their abdomens! (click on all images for larger views). I’d never seen their like before, so I had to hit the books to try to figure out what I’d photographed. It turns out that they are Cerastipsocus venosus nymphs, commonly referred to as “bark lice”. They are considered beneficial bugs in that they feed on fungi, lichen and other organic materials. The adults are winged. Here’s a page containing information on a couple of species.
Recently, I’ve posted quite a few photos of Misumena vatia spiders, but this one is a bit different. Check out the tiny fly sitting on the spider’s back! I didn’t see it until I downloaded the photo and put it up on my screen. Once again, I had to get out my books and do some searching on the web to find out more. It turns out that there is a family of very tiny flies, the Milichiidae, some of which are kleptoparasites that hang out around predators such as spiders, assassin bugs, and robber flies. Some of these insects stake out a spot on a spider web so that they do a bit of scavenging. Others will actually sit atop either the predator, or the prey, waiting to move in for a meal. I suspect that’s just what this little fly is doing and that it must be some species of Milichiidae. When I began looking for info on these flies, I noticed references stating that these flies seemed to be particularly attracted to stinkbug prey (see the last paragraph on the page I’ve linked to). That’s of particular interest as that is just what this spider has caught. I don’t actually see that many stinkbugs being killed by flower crab spiders such as the above, and this is the first time I’ve seen one of these flies atop a spider, so perhaps there is a connection between these flies and stinkbug prey. In future, I’ll definitely be watching for these tiny scavengers.
Tags: Cerastipsocus venosus, bark lice, Misumena vatia, Milichiidae, kleptoparasite, stinkbug