Every thing that God created has a purpose, even if it does not make much sense to us. Take this story for example:
Slate.com has an amazing story about mosquitoes—"hypodermic needles with wings," as they call them (shudder). Here you find a staggering look at the intricacy of creation—even a fallen creation.
Most of us see mosquitoes as a menace, in that they do spread disease and cause death. But just when you long for them to be wiped from the face of the earth, you have to consider this little fact: "Their huge numbers of larvae feed small fish, and those small fish feed big fish, and those big fish are the primary source of protein for much of the developing world." Like I said: "the intricacy of creation—even a fallen creation. Read Genesis 1: 20-23, when God created even the mosquitoes he said it was good!