The milkweed plant is a host plant for a variety of other insects, not just the Monarch butterfly and caterpillar. The Milkweed Community merits it own page, complete with photos taken in the field of insects that I have found and observed while looking for Monarch caterpillars.
Many insects are attracted to the nectar and pollen of the milkweed flowers, while others feed on the leaves, seeds, stems, or roots. The milkweed plant has attractions from the top of its showy flowers down to the stem, leaf, and root. Predatory insects, such as Mantids and Arachnids are attracted to the abundant prey population, including Monarch butterfly eggs and caterpillars!
This is a large milkweed bug, Oncopeltus fasciatus, (photo #1) one of the two common species of milkweed bugs in North America, the other being the small milkweed bug, Lygaeus kalmii. These bugs use the same orange and black warning colors that Monarch and Queen butterflies use. The markings on the O. fasciatus (photo #1) form a black band, whereas the markings on the L. kalmii form a red X. (not shown.. hope to get a photo this summer). These bugs have a tendency to cluster together which makes them seems bigger and transmits the warning to not eat. Large milkweed bugs have long rostrums which they pierce their food with. They inject enzymes that digest the food for them and then suck up the fluids! Yum !
Colorful milkweed bug nymphs congregating on milkweed pods (photo #2).
The scary looking predator on the right is a Praying Mantid (photo #3). They lie in wait for prey to fly or crawl by and then snatch it up with its long raptorial legs that are lined with spikes. Nymphs feed on aphids and fruit flies, while adults prey upon wasps, butterflies, bumble bees and, incredibly enough, an occasional hummingbird ! I once saw a mantid eating a cicada while it was still alive. I heard this dramatic scene happening before I actually saw it, as the cicada was making its loud noise while it was held in the spiked grip of the mantid's forelegs.
Here is one of the familiar 400 coccinellid species found in North America, Ladybug beetles, this one being a Seven spotted lady bug, Coccinella septempunctata, (photo #4). Ladybugs have the prestigious position of probably being the most abundant predator in a milkweed community. The adults and the larva prey on aphids and small caterpillars. In addition, ladybugs are a beneficial beetle to have in your garden, as they lay their eggs on plant leaves containing their prey, convenient for their larvae upon hatching, and doing the job of parasite control in your garden! Note the tiny red milkweed nymph at lower right of photo.