Orange aphids on milkweed
Milkweeds are commonly infested by the oleander aphid, Aphis nerii. These little orange insects suck the sap out of stems, leaves, and can cause flowers and pods to abort, and can even kill plants. They concentrate milkweed toxins in their tissue more effectively than native milkweed aphids, and studies have shown that beneficial insects are less effective at controlling them. As a milkweed gardener, what are your options?
- Wait for beneficial insects (predators) to arrive - sometimes this approach works and sometimes it doesn't.
- Right plant right place - reduce stress on your milkweeds and they are less likely to be plagued by aphids. Swamp milkweeds require constant moisture, butterfly milkweeds require excellent drainage.
- Don’t fertilize milkweeds - in general, aphids are attracted to plants with higher nitrogen content.
When patience and prevention have been exhausted, it’s time to go a step further. The following options will kill aphids, but will also take some beneficial insects and even monarch caterpillars out, so use the utmost caution:
- Squish - place affected parts of the milkweed plant between thumb and forefinger and drag along the stem.
- Squirt - use water from a hose or strong spray bottle to blast the aphids off the stem (can be combined with the previous option).
- Spray - spray aphid colonies with either horticultural soap or oil, both break down quickly but the soap is more likely to burn foliage. To prevent damage to insects elsewhere on the plant, consider cupping the part of the plant you are spraying in the palm of your hand.
- Another commonly found orange bug of milkweed is milkweed bug. They can be numerous but do not cause serious damage to plants. No control is necessary.