Notable features: This deer-resistant plant grows best in moist but will tolerate average soils, and blooms for about a month mid-summer. Later, large pods form which will break open to reveal seeds that will float away in the wind. Large numbers of swamp milkweed can often be seen growing in wetland settings. Monarch host plant!
Attracts: The flowers are very popular with many kinds of insects, including bumblebees, honeybees, long-horned bees (Melissodes spp., Svastra spp.), Halictid bees, Sphecid wasps, Vespid wasps, Tiphiid wasps, Spider wasps, Mydas flies, thick-headed flies, Tachinid flies, Swallowtail butterflies, Greater Fritillaries, Monarch butterflies, and skippers. Another occasional visitor of the flowers is the Ruby-Throated Hummingbird. All of these visitors seek nectar. Some insects feed destructively on the foliage and other parts of Swamp Milkweed and other Asclepias spp. (milkweeds). These insect feeders include caterpillars of the butterfly Danaus plexippes (Monarch), Labidomera clavicollis (Swamp Milkweed Leaf Beetle), Oncopeltus fasciatus (Large Milkweed Bug), and Aphis nerii (Yellow Milkweed Aphid). The latter aphid often congregates on the upper stems and young leaves.