Q • The stems of my milkweed are covered in small bugs, should I be concerned?
The insects you are seeing are probably aphids. They come in multiple colors, usually green, red or brown, are tear-drop shaped and have two distinctive tail-like protrusions on their hind side.
The sight of insects coating our plants can be unsettling, but aphids are easily controlled. A sharp blast of water with a hose can dislodge them, and the insects struggle to return to their perch. A cotton swab dipped in isopropyl alcohol can also be used to kill them on contact. Large populations can be sprayed with a horticultural soap or oil. Repeat every two to three days to ensure small populations do not reestablish themselves.
Alternatively, if your plant is unbothered by aphids, simply leave them be. Their presence will help to attract beneficial insects such as ladybeetles. Aphids are a veritable buffet for these predators, and small aphid populations can build a bank of natural pest control that will feed on other pests once they clean up your aphids.
Write to the Missouri Botanical Garden's Center for Home Gardening at firstname.lastname@example.org or the Horticulture Answer Service, 4344 Shaw Blvd., St. Louis, MO 63110.