You might also try the Fruit Fly/Gnat traps - basically they are just yellow cards with sticky stuff on them. The little buggers (pun intended) land on them and can't get away! Mwuahhhahhhahhhahhhahhhhhaaaaaahhhhhhh

Oops, sorry got carried away. Anyway, they are inexpensive and can be found at most garden stores. Make sure you set it horizontal and not vertical, it really does make a difference.