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| This little guy, about 3 mm. long, on gumweed. |
I counted 8 legs, but I sent it in to BugGuide, and they count 6 legs and two antennae, which makes it not an arachnid.*
Ken Wolgemuth, on BugGuide, says it is "an aphid of some sort."
Interesting: I've seen many black aphids, but always in a mass covering stems and leaves of a whole plant. I've never seen (that I knew of) one out for a walk on his own.
Now this, I know for sure, is a spider:
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| Fat house spider, Steatoda, probably bipunctata, probably female. On the wall above my desk. |
*Update: not 6 legs and 2 antennae; they're 6 legs and 2 "corniculi, a pair of tubes that come off the back of an aphid's abdomen," as Christopher Taylor tells me in the comments. He adds that they may be used to release chemical compounds.
From Wikipedia: The cornicle (or siphuncule) is one of a pair of small upright backward-pointing tubes found on the dorsal side of the 5th or 6th abdominal segments of aphids. They are sometimes mistaken for cerci. They are no more than pores in some species.Thank you, Christopher!
These abdominal tubes exude droplets of a quick-hardening defensive fluid containing triacylglycerols called cornicle wax.
What you presumably counted as two of the 'legs' were the corniculi, a pair of tubes that come off the back of an aphid's abdomen. I think they're used for releasing chemical compounds.
ReplyDeleteThanks! I've updated the post. And now that you tell me, I realize that I've seen these on the aphids in my garden, without knowing what they were.
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