Animal Suicide

Can animals willingly kill themselves? And if they commit suicide, would it be out of an instinctive urge or depression? Animals have a lot to be depressed about, but I'm unsure if they're considering the global destruction of wildlife when they decide to take the leap. I'm guessing dogs or cats might have the capacity to feel sad when they're hungry or their owners are away, but surely that isn't enough to make them kill themselves. I've never heard of a dog or cat kill themselves because of animal abuse, which would hypothetically be a popular excuse to commit suicide for an animal. Anything lower than a cat or dog, I think it's unlikely that it can be depressed.

I think insects don't have feelings. Spiders kill their mate just for fun. Why do you think they call them Black Widows? I know spiders aren't insects, but I doubt the mental capacities of a spider and ant differ greatly.

I've actually seen insects kill themselves for no reason at all. When I was six, my friends and I used to play a game called Learn To Fly. We sat around a picnic table and there was always a sparse population of ladybugs on the table. We would take a cup and gradually guide the ladybug to the edge of the table. Then we'd obstruct the ladybug's escape with the cup, giving her just enough space so that she could decide to stay on the table. Almost every time, the ladybug would scurry over to the edge and jump to her death, completely disregarding the function of her wings. We eventually agreed to stop, because we decided that these were handicapped ladybugs who might have lost their wings, and it was amoral to take advantage of the disabled. However, it's not like we pushed them off the table; we gave them the opportunity to stay in a closed, albeit small, space but they would rather jump off, with or without their wings. Maybe they were sad because they lost their wings.