Bugs do have blood, but it is very different from our own. Human blood has red blood cells in it, which are responsible for taking oxygen and carrying it throughout our bodies. The red blood cells are red because they contain hemoglobin, which is a special protein that actually binds the oxygen.

Insect blood, which is called hemolymph, contains various nutrients, hormones, and other things, but does not have any red blood cells or hemoglobin. That is why it is not red in color, and instead is rather clear.

Insect blood does sometimes have some very light pigments in it, probably coming from plants that they have eaten, and that is why it sometimes looks yellowish or greenish. When you squash a housefly and see red, that's not actually due to their blood-- it's the result of red pigments from their eyes!

Insects also have an open circulatory system instead of a closed one. This means that they don't have any arteries or veins, and instead their blood just flows more openly throughout their bodies.

Insects don't have blood exactly like ours, but theirs does some of the same jobs, transporting things throughout their bodies. Their blood moves nutrients, waste products, and hormones. They have a heart, but it is near their backs instead of near their front like ours. While our blood stays in tubes all the time, some of their blood squishes around in an open space called the hemocoel ("blood space").

Instead of using blood to move oxygen and carbon dioxide, their air tubes (which are spread around their bodies) take in oxygen and get rid of carbon dioxide. Blood can be different colors. Our blood is red due to hemoglobin, the stuff in our red blood cells that lets us move oxygen and carbon dioxide. Since insects don't move these gases in their blood, their blood doesn't have hemoglobin and is generally not red.

Here's a picture of the tracheal system: tracheal system

Why do you think we don't breathe through holes in our sides like insects do?