When I returned from my visit to California in late August, I found one of the swamp milkweed plants covered with aphids. As I reported in a previous blog, this attracted not only parasitoid wasps, but predatory ladybird beetles and lacewings, who laid their eggs on the plants.
Almost three weeks later, the aphids have almost disappeared, except for those on a couple of milkweed pods. There are huge numbers of aphid mummies, parasitized by the wasps, and it looks like the larval predators of the beetles and lacewings have cleaned house.
The following slideshow is a sort of time-lapse sequence of what has occurred over the past two weeks as the last instar of Asian ladybird beetle larvae pupated on the leaves and pods of the milkweed and finally emerged as an adult. After more than 10 days of pupation, they are just now starting to emerge, and I caught one of them in the act of shedding its pupal case. The beetles are uniformly yellow-orange when they emerge, and gradually get their spots over the next few hours.
Beetles go through a metamorphic change during the pupal stage, just as butterflies and other insects do. The body plan is reorganized, and the adult that emerges from the pupal case bears no resemblance to the larval stage.
(The slideshow loops continuously, but if it doesn’t work in your browser, hover your mouse over the photos or click on the forward, backward, or pause buttons to play the slideshow.)