Pests	Description	Control
Aphids	Small, pear-shaped insects with long legs; often pale green to white; may be winged or wingless; secrete a sticky honeydew; found on new buds, rapidly growing tips, underside of leaves near veins; they suck plant juices, reducing vigor, stunting plants, and transmitting diseases.	Squashing; heavy spray of water; soap spray; homemade spray; predators (brachonid wasps, certain predatory midges, green lacewings, ladybugs).
Spider Mites	Nearly microscopic (less than 1/16 inch) arthropods with four pairs of legs as opposed to an insect's three pairs; create webbing strung between the leaf and stem; damage appears as leaf mottling; thrive in hot dry seasons and prefer foliage plants.	Repeated heavy spray of water; predators (predatory mites).
Whiteflies	Tiny, delicate, white-winged insects that feed on a wide range of plants; in large numbers, they'll rise up in a white cloud when disturbed; immature stages look like transparent to opaque white dots on underside of leaves; adults congregate on tips; damage similar to that of aphids.	Soap spray; yellow sticky traps; predators (Encarsia formosa wasps).

Pest Sleuths

Some schools also report success after carefully experimenting with homemade sprays containing hot pepper, garlic, and other strong substances. A number of greenhouse pests, particularly whiteflies, can be lured to yellow boards or cardboard hung throughout the greenhouse and covered with Tanglefoot, a thin layer of axle grease, or another sticky substance.

Natural predators or biological controls can discourage populations of certain greenhouse pests. Ladybugs, praying mantises, and other beneficial insects, if properly introduced, can keep pest populations down, and can provide fascinating fuel for investigations such as the activities in Pest Sleuths.

table of contents