Aphids on house plants may be removed by cleaning the stems in your fingers or brushing with cotton swabs dipped in water or alcohol. If no aphid predator or parasite life stages are present and the level of plant damage is objectionable, chemical sprays are warranted. Two very safe materials are Insecticidal Soap and horticultural oil sprays. They kill aphids only for an hour or so, and coverage must be thorough for good control. Repeat applications are helpful.
Systemic insecticides are most effective for killing leaf-feeding aphids.
Contact insecticides are preferred in the control of bark-feeding aphids. Regardless of the insecticide you choose, be sure the type of plant you want to spray is listed on the label and that aphids are listed as a pest. Be sure the chemical is labeled for indoor use and the pest and plant you want to spray is on the label. Remember that insecticides are not discriminate. They kill beneficial insects as well as aphids, and aphids can bounce back much more rapidly after an insecticidal spray than their enemies.