Last week we brought home broccoli, cabbage and kale from the CSA. Hitching a ride were a few caterpillars.
E noticed one of the caterpillars was sitting on something yellow that looked sort of egg like, but caterpillars don’t lay eggs! Hmmm!…….
We looked at the yellow stuff under the microscope and we could see the caterpillar was spinning silk around these little yellow egg like things. A few web searches later, we determined the caterpillar was a Cabbageworm (hence getting so many with our broccoli, cabbage, and kale) and the little yellow things? Those are parasitic wasp larvae, Cotesia glomerata.
The adult wasps lay their eggs inside the caterpillar. At first the caterpillar continues to eat and grow. Then the wasp eggs hatch and begin to eat the caterpillar’s insides. At some point, the caterpillar stops eating and in about 24-36 hours the wasp larvae eat their way out of the caterpillar. The wasp larvae then spin little yellow cocoons around themselves.
You would think the ravaged caterpillar would be dead at this point, but somehow the wasps have created the perfect zombie. Once the wasps have their cocoons spun, the caterpillar spins additional webbing over them and stands guard for another 24 hours or so before it finally dies.
We really hoped to watch a caterpillar metamorph to a butterfly, so we were disappointed to find all three of our caterpillars were hosts to the witch doctor, Cotesia glomerata.
It was a fascinating find. I took some video and I’m still working on getting it uploaded to the blog so perhaps this post will get an update.
Wishing you many great science discoveries!