After successfully growing just one milkweed plant in my backyard last year, I was excited to have dozens dotting the yard this summer.
But sadly, the plants remain pristine, with no sign of the munching monarch caterpillars that use milkweed as its sole food source, and the reason I wanted the plants to thrive.
Elsewhere, in a raised bed, it was equally exciting to watch one good-sized dill plant grow. Dill is a wonderful herb to flavor foods and I looked forward to using it with steamed green beans and other dishes, and saving the seeds to grow more plants next year. But someone got to it first.
A black swallowtail caterpillar has been devouring the dill and while I won’t have my favorite flavored green bean dish, the sacrifice is worth it, if the caterpillar makes it to adulthood. I’ve been monitoring it almost every day and worry when it disappears, thinking a bird has made off with the now chubby “cat.”
So far, it always seems to reappear, and while the dill is nearly gone, parsley and Queen Anne’s lace grow nearby and could serve as another host plant for my swallowtail caterpillar. They also eat fennel, carrot tops and even the noxious wild parsnip.
The wider menu option for swallowtails is one of the differences between those caterpillars and monarchs, which use only milkweed as host plants. The two caterpillars are similarly colored in yellow, black and white, but the swallowtail’s coloring is more spotty, with a green-toned background, while the monarch’s stripes are more defined.
As adults, monarchs and swallowtails are quite distinct, with the monarch butterfly’s stained glass-like wings in black and orange, with spots of white, compared to the predominately black swallowtail, with blue, white and spots of yellow or orange.
Learn about the central role Iowa could play in the proposed “Monarch Highway.”