Well, you aren't actually looking at cotton, nor is it some sort of fungus or exudate from the tree. What you have stumbled upon is a colony of Woolly Alder Aphids, Paraprociphilus tesselatus.
Here's a close-up of one of the darlings:
In this very personal shot, the critter definitely looks aphid-like, what with its creepy-looking head and accordion-like body. Bhhhh (shudder) - the stuff of nightmares - it's a good thing they are so small.
The white fluffy stuff is actually a waxy substance that the insect exudes from its abdomen, and it is a defense mechanism. Let's say a ladybug or lacewing comes flying along, thinking it's going to have a nice meal of plump, juicy aphids. A quick grab and the predator is bound to end up with nothing more than a mouthful of waxy fibers. Ick. That's enough to snuff any aphid-craving.
I first encountered WAAs around my second or third fall in the Adirondacks. At that point, all I was seeing was tiny bluish-white fuzzballs drifting about the air. They were easy to intercept with a well-placed hand, and up close they were kind of attractive, in a wispy, pale blue and white sort of way (obviously, up-close in the hand is not the same as up-close and zoomed in with a macro lens). It took another two or three years to get an identification nailed down, and now it seems information about them is everywhere on the internet. I didn't see my first colony until about a year ago, and now I see them with fair regularity.
Like other aphids, WAAs have their ant shepherds, and they (the aphids) suck sap from their host plants. But, from what I've been able to gather, they are not particularly damaging, at least not on a landscape scale. So, if you have some on your alders, I'd say just appreciate them - afterall, if you don't look too closely they are really rather attractive, in a wispy, pale blue and white sort of way.
Fascinating! But I liked them a lot more before the close up...
ReplyDeleteThese almost resemble Ceratiomyxa fruticulosa--a slime mold--at least from afar. That's what I thought this was when I first saw the picture!
ReplyDeleteOooo. Very cool. I'll have to keep an eye out for them. Thanks for the post.
ReplyDeleteI googled "white fluffy stuff on alder twig" and found your interesting blog. This, however, is not what I am seeing here in BC, Canada. The white fluffy stuff is all around on a frsty morning, only on the dead twigs, and it is not cold, not frost, and feels like candy floss, except even more fragile. Any idea what that is?
ReplyDeleteCisca - it sure sounds like the waxy outer coating of the aphids. Do you have any pictures of it?
ReplyDeleteI can't think of anything else it could be. Lichens would not be quite that fragile, and any fungus I can imagine wouldn't be floss-like.
Of course, there's always the possibility that BC has stuff that we don't have here in NY.
Here in the States we have County Extension Offices, which are folks who deal with all sorts of things, like agriculture, pests, etc. If you have something like that near you, or a local forestry college, you could try sending them a sample.
Good Luck!
Found and photographed this on alders today along a river in northern New Hampshire. Thanks for the explanation! - Kalmia
ReplyDeleteKalmia - they are pretty cool, aren't they? Glad I could help. :)
ReplyDelete