Thursday, September 1, 2011
A Slow Day at Buck Mt. Creek
Has to be a slow day when I start off with pictures of an adult Dryopid beetle! What's odd to me is that when I found these in samples the last couple of years, they always looked totally black: not so in a close-up photo. They actually have a very nice pattern.
The Dryopid beetle is distinguished from a "Riffle Beetle" (Elmidae) by the size -- Dryopids being the larger, around 1/4" in length -- and by the antennae. Dryopid antennae are short and stubby vs. the "normal" antennae of the Riffle Beetle (which are segmented and red). Here's a good look at the Dryopid antennae.
I really had to "hunt" for insects today: on a lot of rocks I found nothing but snails. Obviously, I was spoiled by the rocks in Montana which often had 20-30 insects calling them home. And, in all honesty, I didn't find a whole lot today. The dominant taxon? The "common stonefly," genus Acroneuria. Actually, they're already quite a bit bigger than they were at the start of the summer -- but they won't hatch until early summer next year. Acroneuria abnormis.
I saw flatheaded mayflies, but not in great numbers, and they were all genus Maccaffertium. Then there were fingernet caddisfly larvae and a couple of small minnow mayflies: the Acentrella nadineae are still hanging around.
I did find a fairly mature spiny crawler nymph, genus Serratella. Note the rich colors and patterns, and compare this to the photo I posted of the Serratella I found in the Rivanna river on 7/19. Remember that this is usually the only genus of spiny crawler that we find in the summer.
I also found some brushlegged mayflies, and they were also pretty mature. They were crawling around in the leaf packs along with the stoneflies. This is the habitat they seem to prefer.
One final photo -- and this is NOT an aquatic insect! This scary critter was on my windshield when I got back to my car. Surely there's some naturalist out there who can tell me what this is. I've never seen one before -- nor do I care if I ever see one again!