Gardeners must actively monitor their crops, watching for the first sign of damage before insect populations get too high. Traps and attractants often appeal to an insect's needs for food, shelter, and reproduction. One type of mechanical trap is a sticky barrier, which can be placed on the trunks of trees and woody shrubs to prevent crawling insects from causing damage. One type of monitoring trap consists of sticky paper on stakes. The paper attracts insects because of its color or because of a sex pheromone that attracts the insect.
Most sticky traps are yellow, a color which seems to attract more insects.
The gardener frequently lifts the shingles to remove and destroy the bugs. A disadvantage of traps or attractants is that they may trap beneficial insects. Also, while some traps may be homemade using simple, inexpensive materials, others are expensive and must be cleaned or replaced periodically. Many traps and attractants are available on the market. A forceful stream of water will sometimes dislodge insects such as aphids and spider mites from foliage and plant stems.