While milkweeds are most famously known for serving as a host plant for the Monarch caterpillar (Danaus plexippus), they are also host to the Oleander aphid (Aphis nerii). Late-summer oleander aphid populations on milkweed are winding down for the year. The final remnants of these aphids can still be found on numerous milkweed species including swamp milkweed (Asclepias incarnata), common milkweed (Asclepias syriaca), and butterfly weed (Asclepias tuberosa).
The oleander aphid is an interesting animal. Adults are all-female and give birth to live young called nymphs. Each nymph is an identical clone of the parent and subsequently molts four more times before reaching maturity. When aphid populations explode as they can quickly do, winged individuals (called alates) develop allowing them to fly off and find another suitable home to repopulate. As such, a few oleander aphids on one milkweed plant can quickly turn into hundreds and thousands of aphids across many plants. See the congestion and carnage on milkweed seed pods below.
While the aphids do not appear to significantly hinder the growth and flowering of milkweed plants even in this summer’s droughted conditions, they are excellent at exuding copious quantities of honeydew which leave a sticky sheen on leaves.
Thankfully, Mother Nature provides numerous natural enemies of the oleander aphid, including lady beetles and their larvae, parasitic wasps, and lacewings, among others.
Just as aphids form wings when they need to explore life elsewhere, milkweed plants also have a unique method of dispersal. Asclepias seed pods are filled with seeds that have a coma comprised of a series of silky strands. The coma enables seed transport via the wind to new locations where each one will hopefully germinate and grow.