Most insect problems on annuals are caused by aphids, spider mites, white flies or caterpillars. Aphids are small, soft-bodied insects usually found on the stems and the underside of foliage of plants. The most common aphid on annual flowers is light green in color with wings present only at certain times of the year on the adult insects. Aphids feed by sucking sap from the stems and leaves of infested plants and can cause heavy loss in certain situations. Aphids may be controlled by spraying with Malathion, Diazinon or other registered insecticides on a weekly basis until the population has been controlled.
Spider mites are tiny relatives of insects usually only visible with a hand lens.
These tiny creatures suck the sap from the plant and congregate on the lower leaf surface. Under heavy infestation, leaves will have a whitish cast. Webbing may occur in severe infestations. Spider mites may be controlled with weekly sprays of Kelthane, Orthene or Diazinon. White flies are tiny, white, flying insects that usually are found on plants in sheltered areas or in greenhouses.