Garrote spider

Garrote spiders grow no larger than a human fingernail across. They are usually found in subterranean ecologies and are colored similar to the rock around them. This makes them nearly impossible to see.
Garrote spiders prefer flying prey. They will rapidly spin webs across a section of cavern up near the ceiling, leaping from wall to wall fast enough to surround an unknowing victim in a few seconds time with the webbing, which is only a few molecules thick and stronger than steel. Any prey that cannot hover will fly into the webbing and be sliced apart. If the prey can hover, the garrote spiders make an ever narrowing net until the wings are lacerated, and the flyer falls, sliced apart by the webbing below it.
The spiders then feast on the kill for weeks even implanting young. 
Garrote spiders are sought after for their webbing which can be used with careful manipulation to make impressive tools, weapons, and armor. They only mate with a single mate at a time, but if one dies, the other will seek out a new mate. Their reproductive cycle is five months. The spiders themselves are easy to kill. Unless the egg sack has just hatched releasing up to six new spiders, it is rare to find more than a mated pair in any long stretch of tunnel.