Male Goldenrod Crab Spider
This crab spider was on the kitchen counter on July 5[1], strolling along just as bold as you please.
It appears to be a male goldenrod crab spider, Misumena vatia.
I’m basing his sex on the fact that his carapace and 4 front legs [2] are a dark reddish-brown, while the abdomen is yellow with reddish bands running along its length. The females look quite a lot different, with a larger abdomen, carapace and front legs roughly the same color as the abdomen, smaller pedipalps, and considerably larger girth. (Edit: I eventually found a female of this species, the page about her and her babies is here),
Goldenrod crab spiders are pretty variable as to color, because they can actually slowly change color to a limited extent (from white to yellow). This is important, because
(a) they hunt by hanging out waiting for insects to wander by so that they can nab them,
(b) a good place to wait for wandering insects is in flowers, and
(c) a large proportion of flowers are either yellow or white, so changing to some shade of those colors is good camouflage.
Of course, on flowers of other colors (like, say, red or purple) they stand out like sore thumbs, but them’s the breaks. This sort of limitation is actually pretty common for animals that do the whole “chameleon” thing – it is fairly easy to toggle between two different colors, like white and yellow, or green and brown, because that just takes one or two colors of chromophore that can be activated or deactivated more or less en masse. Fine control of a number of colors and many subtle shades would be a lot harder.
—
[1] We may have been getting an unusual number of small arthropods in the house at that time, because the dog had destroyed one of the kitchen window screens over the winter. We routinely get 3-4 feet of snow in the winter, so that while most of the time the windows are way too high for him to reach, there are times when the snow pack is deep enough that he can rear up and claw at the window to let us know that, hey, it’s cold out here, I’d like to come in now. So, anyway, that window doesn’t have a screen anymore. And, right around July it starts getting hot enough that it is more important to open the window to let a breeze through, than to keep it closed and exclude insects. And, when it is open, it is an easy hop for, say, a crab spider to get from the cedar tree outside to the windowsill.
[2] Actually, he only had 3 front legs, having lost one somewhere along the line. The missing one would have been reddish-brown too, though.
Comments are closed.
Dr. Mark Hunter, a milkweed expert at the Univ of Michigan, recently told me there are pink-ish crab spiders. (The topic came up when I showed him a photo of a pompilid wasp on a swamp milkweed – he said the wasp was there to prey on the crab spiders.)
Are these a separate species? What color changes can they manage? (Milkweed blossoms come in a spectrum from very light pink to magenta.)
I understand that there are a bunch of different species of crab spiders that hang out in flowers, so I expect that the pink ones are not the same species as the yellow ones (although they are probably closely related). I haven’t seen any of the pink ones yet, but that’s probably because I haven’t seriously looked at a lot of the appropriate-colored blossoms.