This question was relayed to me by Zooilogix from a young reader. The answer is yes, insects do have eyes-they even have two kinds of eyes!
The first kind of eye that insects have are called Ocelli. This photo of a wasp head shows the characteristic arrangement of 3 ocelli in a triangle between the larger compound eyes. Most adult insects have two compound eyes, just like we humans have two eyes.
Both kinds of insect eyes–ocelli and compound eyes– function to detect light and movement, just like our eyes. Unfortunately, there are so many different kinds of insects, and kinds of insect eyes, that a discussion of them all without boring everyone, or sounding like a textbook, is going to be impossible.
So let’s just focus on the cool stuff, eh? I’ll put links at the bottom for the people that really want to know what an apposition eye is.
Human eyes are mostly liquid, and use the iris to adjust how much light gets in. You can see this at work if you look at a bright light and then away when looking in a mirror–your pupil will get smaller and bigger, depending on the light.
Insect eyes are mostly solid, and are made up of many individual parts. An insect eye has a sort of bumpy appearance–some insects have over 40,000 individual units to a single eye, which is why it’s called a compound eye. They use pigments traveling up and down inside the eye to regulate how much light gets in. This can make some really neat patterns on the insect eye. Because the eye is solid, it isn’t as easily injured by a poke as our fragile liquid eyes.
Freaky-cool insect eye modifications:
Whirligig beetles (Gyrinidae) actually have 4 compound eyes! Gyrinids live and swim on the surface of ponds and streams. One set of eyes is for seeing above the water, and one is for seeing below the water. (The red line in this photo shows where the water line is when the beetle swims) Oddly enough, these beetles only appear to have 4 eyes–each of their eyes splits in half during development. One half migrates downward onto to the beetle’s chin, and the other to the top of its head.
If you had 2 extra eyes, where would you put them?
You can learn more about gyrinid beetles at Hilton Pond’s website.
Another neat variation on the basic plan is found in dragonflies. Their eyes just about cover their whole head! What would having a head that’s almost all eyes be like?
Our last example of cool insect eyes is found in a group of flies called Diopsidae. They have their eyes out on stalks!
I’d have a lot of trouble with these kinds of eyes–I tend to bump into things a lot, and it would really be a drag to break one of your eyes off!
So there you go, a very brief intro to insect eyes for a young’n.
Some additional insect vision resources:
- Ask a Biologist: Butterfly vision
- Ask a Biologist: What do insects really see?
- San Diego Museum’s online vision exhibit
- An animated illustration of how insect compound eyes work
- A nice explanation of the different types of compound eyes
More advanced resources: