A SHORT COURSE IN INDOOR PLANT PESTS--PART II

The two-spotted red spider mite is the most out of control insect today. It is common in greenhouses and on many outdoor crops. Spider mites are tiny, 8 legged critters. They are most common in hot, dry conditions which describes many homes in the winter!

One reason this pest is so out-of-control is that our abundant use of pesticides have destroyed many of its' natural predators. In fact, some pesticides seem to stimulate reproduction! Outside the female lays eggs which overwinter. Inside conditions mean these pests can live year-round. A new generation is produced every two weeks.

Mites feed by rasping and piercing the foliage of the plants. This results in oozing juices. Typical symptoms include yellow leaves, or stippled leaves with yellow/red spots on the surface. The underside of the leaf may show a fine webbing. Another way to spot them is to hold the plant over a white sheet of paper and gently shake it. If tiny red spots appear on the paper, you have mites.

Since most of these mites are resistant to pesticides, this has little value. The most effective way of controlling them is to keep your plants well watered and to mulch the surface of the soil to help it retain moisture. When conditions are humid, natural diseases occur which helps to control the mites. If you find the characteristic webbing, wash the plants carefully being sure to include both upper and lower surfaces of the leaves. Changing your watering practices should reduce the population significantly.

Until December, good gardening to you.

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