This native ladybeetle is feeding on the contents of an insect or spider nest. Spotted ladybeetles, both adults and larvae, are voracious predators of aphids, but will also eat a variety of other foods including insect eggs and pollen. I have found them to be especially common on early blooming dandelions, when the flowers are sometimes covered with these very small ladybeetles. Dandelions provide an essential food source (pollen) until aphids and other invertebrate prey is available.
I also find them quite often on milkweeds, and because milkweeds seem to attract a lot of insects, including those who will lay their eggs on the plants, spotted ladybeetles are therefore also attracted to milkweeds.