Well, now you can do it with a city of people! The “game” ends when you blow up the tanker truck.
I used a fresnel lens.
Didja have one of those giant ones that could also melt asphalt in seconds?
Dude, that’s sick!
Thanks! 
I’m ashamed to say that I did toast a few insects when I was a kid.
I called my utensil a “maggot-frying glass.”
Speaking as one who, as a kid, regularly lusted for things in the Edmund Scientific catalog: I so badly wanted one of those melt-asphalt-in-seconds fresnel lenses! I still do! I’ve heard they can be salvaged from rear-projection TV screens. Maybe the local dump can help me out here.
The closest I ever got was a sheet magnifier about 8"x12" or so. It didn’t melt asphalt, but it would ignite nearly anything flammable almost instantaneously. T’hell with frying ants - with something like that you could fry badgers.
It was about 8" across.
I remember using a magnifying lense to “write” things on a tennis ball. You could burn the fuzz right off.
We didn’t have fire ants back then… so we made our own.
Ants give off a yummy roasted coconut scent, when burnt.
Ahhh, few things more entertaining than vaporizing ants on a really hot day.