2009-09-17 / Local & State

Late Season Insects


As summer comes to a close, there are a number of insects that become more visible. A quick walk around the native plant garden leads to the discovery of two. The brown marmorated stink bug is visible on many of the ornamental plants in the MAEScapes Garden. This insect is a non-native true bug that has spread throughout eastern Pennsylvania and parts of the northeast. I have seen minimal plant damage on ornamental plants and have not heard of serious damage on small or tree fruits. Brown marmorated stink bugs often become nuisance pests when they congregate in late fall to overwinter. This often occurs in homes. Unless there is significant plant damage, or a population of biblical proportions on the house, I would avoid an insecticide application. Further information can be found at: http://ento.psu.edu/extension/factshe ets/brown-marmorated-stink-bug

The Chinese mantid (Tenodera sinensis) and the Carolina mantid (Stagmomantis carolina) have reached maturity and can be found now. There was a Chinese mantid in the plants outside the office. This mantid has a light green stripe on the side of each wing (color varies though) and is longer than the native Carolina mantid. It is a fascinating insect because of its size and appearance. It is predacious on insects, though it can prey on small vertebrates. I do not consider it a beneficial insect in that it is not a specialist feeder on common ornamental plant pests. However, I think they are fascinating insects and interesting to watch. Also, it is not illegal to kill any mantids, but why would you want to!

Though not insects, southern red mites and spruce spider mites are becoming active again. Unlike other spider mites such as two spotted spider mite, oak spider mite, etc., these two species favor the cooler weather of spring and fall. Southern red mites feed on broadleaf evergreens such as rhododendrons, azaleas, hollies to name a few, while spruce spider mites can be found on spruces, hemlocks, fir and other needled evergreens. Both can have a couple of generations before cold weather sets in. At that time, they will overwinter as eggs. You can scout for mites by tapping plant foliage over a white sheet of paper on a clipboard. If present, the mites are the tiny, dark, slow-moving specks. Also, watch for the poppy seed-sized spider mite destroyer lady beetle that feeds on all stages of these mites. The use of a hand lens makes positive identification easier. If the feeding damage (stippling) and the mite population warrant treatment, you can use ultrafine/all season horticultural oil, abamectin (Avid), acequinocyl (Shuttle) or bifenazate (Floramite).

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