Mosquito breeding habitat is a fairly well known. I in summers we hear news reports about dumping standing water our of old tires or empty flower pots. Ever wonder why they lay their eggs there and not larger bodies of water with more food, like lakes and rivers?

Larval (baby) mosquitoes are aquatic insects but they do not breath water like fish or young dragonflies do. Just like whales they live in the water but breath air, so they must say close to the surface or risk drowning. Instead of a blowhole the larvae have a special siphon which they use to suspend themselves from the water’s surface tension. Breaking the surface tension with a drop or two of dish soap will kill any larval mosquitoes by not allowing them to breath.

Culex restuans larvae anatomical diagram. Here you can see both the dorsal (top) view of the siphon, and the side view in the inset.

In larger bodies of water fish and other predators, like giant water bugs, can easily snap the larvae up as they hang, suspended from the surface. If they attempt to hide on the bottom of in vegetation the larvae risk drowning while waiting for the predator to loose interest.

Here are a few videos that I made to demonstrate the principal. Sorry about the background noise in these videos. Laboratory buildings require substantial ventilation systems for health reasons, and they are pretty loud.