Pond Insects
June 12, 2004 4:14 AM Subscribe
Can anyone help me identify some form of pond-based insect life from what may be a pretty bad description? [MI]
Basically, just near my office is an artificial pool (circular, ~3m diameter, 50cm deep, bottom covered in large pebbles). This summer and last there have been what looks like insects in the pool. This year's crop have bodies which are ~8-10mm long and from above look a little like a spider would look from below (a vaguely truncated hourglass, shall we say). On either side that have a single 'leg' which extends for ~10mm from their body, this is perpendicular at rest but is swept back to propel them through the water. They tend to spend their time at the surface of the water (but in it rather than on it) and dive down when disturbed. They also have 2 antennae on their heads (~2mm length). They are a mottled black colour. So can anyone identify what these chaps are?
There doesn't appear to be much other life in the pond, some green algae grew there up to a few weeks ago but has died back. There are a lot more of the things this year than last though they this years are as yet not as big as last. I'm pretty certain the pond has been drained between summers, so it may be that they're pretty hardy fellows.
Basically, just near my office is an artificial pool (circular, ~3m diameter, 50cm deep, bottom covered in large pebbles). This summer and last there have been what looks like insects in the pool. This year's crop have bodies which are ~8-10mm long and from above look a little like a spider would look from below (a vaguely truncated hourglass, shall we say). On either side that have a single 'leg' which extends for ~10mm from their body, this is perpendicular at rest but is swept back to propel them through the water. They tend to spend their time at the surface of the water (but in it rather than on it) and dive down when disturbed. They also have 2 antennae on their heads (~2mm length). They are a mottled black colour. So can anyone identify what these chaps are?
There doesn't appear to be much other life in the pond, some green algae grew there up to a few weeks ago but has died back. There are a lot more of the things this year than last though they this years are as yet not as big as last. I'm pretty certain the pond has been drained between summers, so it may be that they're pretty hardy fellows.
Is it still water? Could they be mosquito larvae?
How Mosquitos Work uses the phrase "Mosquito larvae can swim and dive down from the surface when disturbed," but then again I imagine a lot of things can do that.
posted by Pockets at 12:54 PM on June 12, 2004
How Mosquitos Work uses the phrase "Mosquito larvae can swim and dive down from the surface when disturbed," but then again I imagine a lot of things can do that.
posted by Pockets at 12:54 PM on June 12, 2004
I don't recall mosquitos having big "oars" off their sides, though.
Incidently, cornstarch is hell on mosquito larvae.
posted by five fresh fish at 6:55 PM on June 12, 2004
Incidently, cornstarch is hell on mosquito larvae.
posted by five fresh fish at 6:55 PM on June 12, 2004
This cornstarch against mosquitos, does it harm other pond life, such as dragonfly larvae? Just sprinkle on the water?
posted by Goofyy at 3:05 AM on June 13, 2004
posted by Goofyy at 3:05 AM on June 13, 2004
IIRC, dragonfly larvae don't need to hang about at the water's surface breathing air.
The cornstarch forms a very, very thin film that the mosquito larvae can't poke their breathing tubes through. The water remains oxygenated, though, because the film is gas-permeable; ergo, fish and plants and such aren't killed off. The cornstarch is readily biodegraded, eaten by microbes probably, so it doesn't harm the other lifeforms.
Contrast to ye olde oil-slick method, which kills everything.
I should think a quick googling will find out whether other larvae are harmed. Probably also would let you know how much is needed.
posted by five fresh fish at 10:27 AM on June 13, 2004
The cornstarch forms a very, very thin film that the mosquito larvae can't poke their breathing tubes through. The water remains oxygenated, though, because the film is gas-permeable; ergo, fish and plants and such aren't killed off. The cornstarch is readily biodegraded, eaten by microbes probably, so it doesn't harm the other lifeforms.
Contrast to ye olde oil-slick method, which kills everything.
I should think a quick googling will find out whether other larvae are harmed. Probably also would let you know how much is needed.
posted by five fresh fish at 10:27 AM on June 13, 2004
Response by poster: Thanks Jessamyn, I went back and had a closer look and I think that Water Boatmen must be right. Their waists don't constrict as I had originally thought. Cheers all.
posted by biffa at 6:44 AM on June 14, 2004
posted by biffa at 6:44 AM on June 14, 2004
This thread is closed to new comments.
posted by jessamyn at 5:32 AM on June 12, 2004