ENTFACT-306: Controls For Greenhouse Vegetable Insects  |  Download PDF

by Lee Townsend and Ric Bessin, Extension Entomologists
University of Kentucky College of Agriculture

The warm humid conditions and abundant food in the greenhouse are ideal for pest build up. Problems can be chronic unless recognized and corrected. While insecticides are important tools, successful control of greenhouse vegetables pests relies primarily on cultural factors. Proper cultural practices can minimize the chance for initiation and build up of infestations. Early detection and diagnosis are key to greenhouse pest management, as well as, the proper choice and application of pesticides when pest outbreaks occur. 


Pests may enter the greenhouse in the summer when the ventilators are open. Others may be brought into the greenhouse on new plant material or in soil. Many are able to survive short periods of time between harvest or plant removal and production of the next crop. Cultural controls are the primary defense against infestation. 

Proper cultural practices which will help prevent pest infestations include:

  1. Maintain a clean, closely mowed area around the greenhouse to reduce pests that develop in rank growth.
  2. Remove all plants and any plant debris, clean the greenhouse thoroughly after each production cycle.
  3. Keep doors, screens and ventilators in good repair.
  4. Use clean or sterile soils or ground media, tools, flats and other equipment.
  5. At the conclusion of the season remove all plants and any plant debris, clean greenhouse thoroughly and fumigate.
  6. Inspect new plants thoroughly to prevent introduction insect or disease infested material into the greenhouse.
  7. Watch for leaks or pooled water that can lead to fungus gnat infestations.
  8. If possible allow the greenhouse to freeze in winter to eliminate tender insects like whiteflies.
  9. Avoid wearing yellow clothing which is attractive to many insect pests.
  10. Eliminate infestations by discarding or removing heavily infested material. 


Early detection and diagnosis of pest infestations will allow you to make pest control decisions before the problem gets out of hand. It is good practice, therefore, to make weekly inspections of plants in all sections of the greenhouse. 

Insect monitoring devices are also available. Yellow stick cards (PT Insect Monitoring & Trapping System, Whitmire) are highly attractive to winged aphids, leafminer adults, whiteflies, leafhoppers, thrips (blue cards can also be used with thrips), various flies and other insects. These can be used to alert you to the presence of a pest and identify hot spots in the greenhouse. One to three cards per 1000 sq. ft. in the greenhouse is recommended and should be changed weekly. If you cannot identify a trapped insect, contact your county extension agent for assistance. Mass trapping products such as sticky tapes are also available for thrips, whitefly, leafminer and fungus gnat detection and management.


Revised: 1/04 

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication. 


Photos courtesy Ric Bessin, University of Kentucky Entomology