Here is the article from last September:
Monday, September 27th, 2010Our caterpillars seem to have laid eggs!!! We have cabbage white caterpillars in school. We feed them cabbage leaves, and sprinkle the leaves with a little water each day. The caterpillars seem very happy in their new home. Some of the caterpillars seem to have laid eggs (we didn't know they could do that! we thought it was the butterfly that lays the eggs). Anyway, we are waiting patiently for some cocoons, then butterflies. We hope it's not too cold for them these days.
After some searching on the internet, teacher discovered that caterpillars can't lay eggs!
The answer seems to be that the eggs are injected into them by a parasitic wasp which hatch then eat the caterpillar from the inside out before crawling out (they really look like eggs!) We will have to keep a good watch on these eggs and see what happens!
Check out this article for more information http://www.pbs.org/wnet/nature/episodes/alien-empire/caterpillar-wasps/3415/
Anyway, the eggs are hatching and we are seeing not wasps, but ant-like insects with 6 legs, wings and 2 antennae They look much more like ants than wasps.