Inhumane and cruel? I admit to doing it when I was seven, but would probably not condone it in my son.
Thoughts?

My gut is that killing ants with a magnifying glass does not a serial killer make. As evidenced by the fact that most of us as kids are now fully functioning adults.

However, I do think its a great opportunity to talk to kids about not hurting other living things unless its for our own health. For example, I kill a fly in the house because of possible food contamination.

I remember a Prairie Home Companion piece in which Garrison Keeler talked about a boy throwing rocks at the pigs. They were going to eat them anyway, he said. Pops chimed in with something about they still deserved a level of respect while alive.

On a similar note, it seems, we recently made some marshmallow shooters in our house. I was certain I would not be able to keep the kids from calling them guns and from not shooting each other. But I towed the line and remarkably we now hit targets and shoot into buckets in order to play with the shooters.

I think the ant thing could go the similar route. There are tons of things to set on fire with a magnifying glass that are not living creatures.

The hard question is what will be the response when he does it anyway.

Good point Daddy T, this is a great moment to teach about respect for living things. However I used to shoot grasshoppers with my bb gun and I turned out ok. Burn leaves, they don't feel pain. Or do they?

Good time to teach kids some science why convex lenses converge light, why they magnify things, solar energy Maybe not. It only takes a small spark in a kids head to get them thinking.

If you do decide that burning little creatures with the magnifying glass is ok for your kids, I recommend that you have them target rolly pollies. At first, the just curl up into a ball, but after a few seconds, they pop open like popcorn.

I think that doing such does not produce a killer or maniac out of your child. But kids should learn to value even small insects in the ecosystem. They might not understand it now but these ants play a vital role in our ecosystem. I admit that I did that myself when i was younger but it is not a good act.