Black Swallowtails are common butterflies in the Midwest.Â I see them in cities and gardens as well as in our prairies.Â They lay their eggs on plants in the carrot family: Dill, Parsley, Queen Anne’s Lace, and natives like Golden Alexander (Zizia aurea) and Yellow Pimpernel (Taenidia integerrima)
Here’s a female Black Swallowtail laying eggs.Â She hovers next to the plant without landing on it.
Here’s one of the eggs, on Dill.
In the early instars, the caterpillars are usually dark with a white saddle.
Sometimes I’ve seen lighter ones, with more white and orange coloring.
A later instar
Two caterpillars in position to form their chrysalises
If the caterpillar forms its chrysalis on a rough surface – like a stick – the chrysalis will usually be brown.
If it forms on a smooth surface – like a dill stem – it will usually be green.
During the summer it takes about 10 days from the time the chrysalis is formed until the adult butterfly emerges.Â In the fall, the chrysalis may overwinter and not emerge until spring.
Black Swallowtail adult
Buffalo County, Wisconsin