Aphids on milkweed
Bright yellow aphids with black legs on milkweed are oleander aphid. They cost monarchs indirectly — in Florida trials females laid three times more eggs on aphid-free plants — but the usual cures cost more. Every systemic insecticide tested killed monarch caterpillars on treated plants; pymetrozine still killed half at four weeks, twice as long as it controlled the aphids. Insecticidal soap did not harm the larvae but did not hold aphids below threshold. Prune infested tips, hose or squash colonies after checking for eggs, and let hoverflies and wasps work.
At a glance
- Damage
- Bright yellow colonies on milkweed and oleander tips, honeydew, sooty mould
- Type
- Sap feeding · virus vector
- Settings
- Garden, Under glass
- Threshold
- None — prune, squash or hose; do not spray systemics
- Ally
- Syrphidae
- Rate
- Wild — plant a mix of flowers near the milkweed
How to confirm it
Bright yellow aphids with black legs, antennae, cornicles and tail, packed along milkweed or oleander stems, shoot tips and seed pods. The yellow body with black appendages is the combination UF/IFAS uses to describe this species.
Identification, lifecycle, degree days and every control option are on the full Oleander aphid profile. Not sure it is this pest? Answer four questions about the damage.