Why do bugs bite you?

Question

This is for a report

Answer 1

They smell your body & blood.  They are hungry and suck your blood.  Some insects need human blood to procreate - or mate and spawn young.  

Answer 2

For many reasons, but mostly its self defense or getting some food.

Answer 3

Mosquitoes do it because they need your blood in order to produce young.  

Spiders do it in self defense. If you leave them alone they will leave you alone.

Bees and wasp sting in self defense and to defend the hive.

Parasitic mites and ticks attack prey for their blood. Spreading disease is unintentional but a serious problem is parts of the world.  Some Lice bite us to suck our blood.

Many flies pass their larval stage as internal parasites of man

Answer 4

Some feed on blood or flesh; such as mosquitoes, fleas, biting flies.

Some, like yellow jacket wasps, will bite if you have food (meat juices or fruit juice on your skin, thinking you are food; also in self defense, though the stinger is much better for that.

Some bite in self defense.  Also, I've held Jerusalem crickets in my fist and they bite to get out; I think they were just trying to dig, I don't think they were afraid.  But they will also bite when afraid.