Thread subject: Diptera.info :: Scatella
Posted by Nikita Vikhrev on 31-08-2006 20:45
#1
Moscow region, 31 aug, 2,5mm
S. stagnalis?
It sits on leach with some reason or without?
Posted by Tony Irwin on 31-08-2006 21:46
#2
Scatella tenuicosta - very similar to
stagnalis, but the most distal spot in the wing is shaped like an hour-glass (or Coca-Cola bottle :D). In
stagnalis this spot is more oval. All
Scatella feed on diatoms and desmids, so there's no reason for it to be on a leech - perhaps it's just a good place to view the crowd. (The male is on the leech, the female on the leaf.)
Posted by Nikita Vikhrev on 31-08-2006 21:59
#3
What an easy way to separate two species!
Thank you Tony!
Posted by Tony Irwin on 31-08-2006 22:14
#4
I should point out that not all
tenuicosta show the "waisted" spot. Some of them have a less obvious triangular spot, but in all the specimens I've seen, the spot widens anteriorly (towards R4+5). In
stagnalis the spot can also be various shapes but never widens anteriorly.
And don't forget there are other species with which they can be confused :( though these two are the most common and widespread.:)