Urban wildlife mystery! (ID help needed)
Oct. 6th, 2011 05:47 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
urbpan
Alexis and I went to West Roxbury for brunch on Sunday. Right where we parked I noticed this little dead street tree with polypore mushrooms on it. What's that red stuff? I wondered...
Why, it's hundreds of bright red insects, of course!
I take the massive amounts of red ones to be larvae (or nymphs) and the few dark ones to be adults. These are just a couple mm long, so pretty darn small. Shaped like rove beetles, but much more numerous than I would expect for beetles--I've never seen beetle larvae in maggot quantities before. My best guess is that these are in the Tachyporinae group, but that--as I say--is a guess. Clearly the mushrooms are the focus for the insects--are they feeding on them? It seems likely.
EDITED TO ADD: Wrong wrong wrong! Alexis' superior googling ability turned up a similar "what beetle is this" query, complete with the answer: "Not a beetle at all, nincompoop." To be fair, they've stumped at least two more entomologists in the past few hours. Thrips are usually thought of as plant pests, but these appear to be ones that feed on spores (judging by the way they are swarming over the spore producing surface of the mushrooms). I know virtually nothing about thrips, except that the horticulture director down the hall sometimes mentions them when he is cursing. I should do some more research.
It's always great to find something completely new, especially in the city!
![[identity profile]](https://www.dreamwidth.org/img/silk/identity/openid.png){kind=small}
no subject
Date: 2011-10-06 11:22 am (UTC)The adults certainly look like staphs, not tachyporines, tho. Many adult staphs are predatory on larvae of whatever they can find, so I kind of wonder whether they're guarding those grubs or snacking on them.
no subject
Date: 2011-10-06 11:49 am (UTC)no subject
Date: 2011-10-06 04:05 pm (UTC)no subject
Date: 2011-10-07 03:12 am (UTC)The very charming world expert on thrips (http://www.csiro.au/people/Laurence.Mound.html) works down the hall from me, and has two very useful thoughts on these photos:
1) They're probably Hoplothrips or a closely-related genus (Hoplandrothrips linked below is a good candidate)
2) Although massing behavior like this is rare in thrips, it has been previously documented in a South American species-- several adults tend a huge mass of nymphs, guarding them at night in small tree crevices and herding them, by day, over to delicious lichen or fungus patches where the adults stand guard, gaucho-like, over the dense herd of spore-feeding babies.
3)FURTHERMORE, the red color is a totally unaddressed mystery in thrips. There are many groups where one concealed, under-bark species will have pale white nymphs, while its sister species feeds in exposed areas and has bright red nymphs like those shown here. That is, this weird "we're exposed so let's be red" pattern has evolved many times in thrips. Nobody knows whether they're actually toxic.
(p.s. the question of whether young thrips should be called "nymphs" or "larvae" is a very sensitive question, since thrips have independently evolved pupation. We tend to reserve "larvae" for the young of truly pupating insects (leps, bees, flies, beetles), but since thrips have their own utterly unique kind of pupation... maybe they should have "larvae" too?)
no subject
Date: 2011-10-07 03:13 am (UTC)no subject
Date: 2011-10-08 12:46 am (UTC)no subject
Date: 2011-10-08 02:52 pm (UTC)no subject
Date: 2011-10-06 12:34 pm (UTC)no subject
Date: 2011-10-06 04:10 pm (UTC)What do I owe you?
no subject
Date: 2011-10-06 04:52 pm (UTC)no subject
Date: 2011-10-06 10:03 pm (UTC)