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  • When Should I Release Trichogramma Wasps

    Created by Kenneth Wilson on

    I don’t understand when to release the trichogramma wasps. It says when moths are out but when is that? When trees are blooming?

    How long does it take them too hatch? Can they be stored if it’s too early to release them?


  • Author
  • #226029

    Eric Vinje


    Trichogramma wasps arrive still developing inside moth eggs on one inch by one inch square(s), or sheet(s) of squares, that resemble sandpaper. Each square contains roughly 5,000 parasites. Depending on temperature conditions during shipping, adult trichogramma wasps will emerge 1-3 days after arrival. If immediate release is inconvenient, the container(s) can be placed in the refrigerator for up to 3 days. DO NOT FREEZE.

    Purchase trichogramma wasps here.

    Trichogramma adults are very small (1/50th of an inch), and once emerged can be seen as tiny brown dots moving around in the container. They are best released in the early morning or late afternoon. Simply place the opened container(s) out of direct sunlight in the area where moths are suspected or seen. To control pests in trees, staple or otherwise attach the container to the tree as high as possible. This will also prevent the square(s) from being blown away by the wind. Ants can be a problem, eating the eggs on the square(s) if found — placing the square(s) in strategic areas should prevent this. Hanging the square(s) on a piece of thread is a solution.

    Check closely for moth activity in the spring (pheromone traps are very helpful for this). If moths are present make regular releases — every other week, or weekly during peak activity — for best results. Once caterpillars are present, other control measures such as Bacillus thuringiensis (Bt-k) may be necessary.

    Hope this helps!

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