tt-117
BY DON MEEHAN
BIOLOGICAL INSECT CONTROL IN GREENHOUSES
Many homeowners are plagued with the problem of how to control insects in their greenhouses or specifically designed plant areas in their homes. The use of insecticides is not very appealing in confined spaces such as these, and when used need very special considerations. One of the techniques which has been talked about through the years has been the Yellow Stick Traps.
These traps rely on certain insects' natural tendency to be attracted to yellow. The trap is very simple and is made of wood or anything thin and flat. It is painted bright yellow (the visual attractant) and is then coated with a sticky substance. They are available commercially or can be made at home.
What kinds of insects can you expect to catch with this system? They are often recommended for monitoring and controlling whiteflies, but will also catch winged aphids, leafminer adults, thrips, fungus gnats and shore flies. It pays to be able to learn to differentiate insects caught, and that may take a hand lens and some training.
The best use of the traps is in a monitoring program, and they are not a total replacement for inspecting plants, but can give you good clues on how pest populations are increasing and decreasing. Traps should be monitored weekly and decisions made about the severity of the pest population. From this information one can decide if pest control strategies need to be adopted.
Traps need to be located near the plant foliage since this is where most of the insect flight activity takes place. Usually just above the plant foliage is best, but some insects can be caught best if the trap is at soil level. Having traps placed by vents and highly susceptible plants will pay dividends.
As a general rule, the more traps the better, but keep in mind these are sticky beasts, and bumping into them is not part of enjoying the greenhouse experience.
Within limits, trap size doesn't seem to matter too much. They can be almost any shape, but most are rectangular for ease of hanging and maintaining.
If you want to make your own traps, the process is easy. The base board can be most any material, but it is best if it is durable material that can be banged around some and can handle moisture. Decide on the size and shape, and make several at one time. Drill holes in spots you will want to hang them from. Paint them with a bright yellow paint such as Rustoleum. Be sure the paint has dried well, then coat the painted boards with cooking oil or motor oil (motor oil smells). This can be brushed on or dipped in a pail, and then left to hang and drip. When you are sure they are done dripping they are ready to hang. Cleaning boards can be done with just soapy water, and should be done on a fairly regular basis so old insects are removed.
To summarize, the keys to all of this are to use these traps as a safe way of helping you monitor and control insect pests. Learn to identify what you are catching, and don't forget to change or clean your traps weekly.
Return to Main WSU Page
Return to Articles Index
Providing Educational Support to the Island County Community