Aphids are another pest that should be scouted for in fall greenhouse plantings. The following is an article on the subject from the University of Maryland.
Monitoring Aphids in the Fall
Throughout most of the year, aphids can reproduce parthenogenically (females do not mate and give live birth to more females). Aphids can give birth to females ready to give birth to more aphids which means aphid populations can build up very quickly. Winged forms can be produced when populations are high to help the aphids disperse to new plants or crops. In the fall, males are produced and they mate with the females. At this time, females lay eggs which overwinter. Aphids in the egg stage are not susceptible to insecticides.
Monitoring: Look for aphids feeding on growing tips, along stems and in flower heads. In heavy infestations, there will be many white cast skins and sooty mold on the plants. Aphids secrete honeydew as a waste product which is a food source for the sooty mold fungus.
Control: Insecticides for aphid control include neem products and horticultural oils. Most of the systemic insecticides labeled for ornamental crops give good control of aphids.
Biological Control: Predators and parasitoids can be ordered from biological control suppliers and released in the greenhouse to help control aphids before populations build to high numbers. The lady bird beetle, Hippodamia convergens, lacewings, parasitic wasps such as Aphidius colemani and the predatory midge, Aphidoletes aphidomyza, are readily available.
Reprinted from the October 30, 2009 edition of the Greenhouse TPM/IPM Bi-Weekly Report from the University of Maryland Cooperative Extension Central Maryland Research and Education Center. For the full article with pictures go to http://www.ipmnet.umd.edu/09Oct30G.pdf