How to make a PET bottle insect trap:
Cut the top (just before the start of the cone) off a 2 liter PET bottle.
Invert the cone and place it inside the straight part of the PET bottle.
Glue the two pieces together, using a glue or silicon.
Add 1 tsp yeast and 1/2 cup sugar to some luke warm water, and pour the mixture into the PET bottle.
Mosquitoes are attracted to the carbon dioxide that you exhale. The yeast feeds off the sugar and emits the same gas, so the mosquito enters the bottle, thinking she will find food there. She cannot then get out.
You can use the same PET bottle design for a fly trap, but fill it with a putrid smelling liquid. For wasps, use a sugar mixture. For fish, put under water, and add a bit of cheese or brea