Wood absorbs moisture and is more susceptible to attack by carpenter ants and termites when in direct contact with the soil. Construction Site Sanitation - removing tree stumps and lumber scraps from construction sites, which are prime food sources for subterranean termites, can prevent problems in the future. Examples of biological control agents are beneficial mites that feed on mite pests in orchards, the milky spore disease that kills harmful soil grubs, and En carsia formosa , a wasp that parasitizes the greenhouse whitefly. Many biological control agents are commercially available. Physical Barriers such as netting over small fruits and screening in greenhouses can prevent crop loss.
Physical barriers are important in termite, house fly, and rodent control.
This technique is used in curbing damage from the grape berry moth. Pest-Resistant Varieties are those that are less susceptible than other varieties to certain insects and diseases. Use of resistant varieties often means that growers do not need to apply as many pesticides as with susceptible varieties. Potato growers control the golden nematode by planting resistant cultivars. Apple growers can save up to eight fungicide applications a year by growing Liberty and Freedom cultivars, which resist diseases.