Controlling Thrips

Thrips

There are many species of pest thrips throughout North America. Unless you have a magnifying glass, you probably won't see them on your plants. Thrips are about 1/25", but you may notice signs of their presence, such as black, shiny speckles (droppings), silvery stippling (masses of tiny discolored scars on plant parts), or, in severe cases, deformed growth.

Magnification shows thrips to be shiny, elongated blackish or yellowish insects. Adults have feathery, fringed wings, and nymphs lack wings. There are many generations per year. Thrips prefer to feed on new, rapidly growing plant tissue where it is easy to hide. Most feeding by thrips causes only slight damage, but high populations can be quite destructive. Thrips feeding can prevent rose buds from opening, and results in deform petals. Certain species spread viruses to tomatoes and impatiens. Thrips also attack asparagus, cabbage, lettuce, onions, peas, flowers, and fruit and shade trees.

Controls

Natural enemies generally keep thrip populations below damaging levels.
Conserve natural enemies by reducing or eliminating pesticide use.
Locate plants away from weedy, grassy borders where thrips live.
Use Insect Control Spray, which contains canola oil.
Keep plants well watered, and fertilize judiciously to prevent overly lush growth.
Dormant oil is a useful control on fruit trees.

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