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Seasons: Spring Insect Pests

Seasons index:

Spring is here and so are the usual springtime pests. The Gypsy moths are a bit more subdued this year, but the Spring Cankerworms ("inchworms") are proliferating. Most deciduous trees (such as the oak pictured below) will recover fully from an insect defoliation but they can be weakened by repeated defoliation. Watch for this in areas where the spring cankerworms are hitting the same trees that were attacked by gypsy moths last year. However, the good news is that even after two successive years of such attacks, most trees will recover.

Another insect pest that seems to have been getting more common in recent years is the European Pine Sawfly. In a few instances the larvae have been observed attacking White Pine, which is not usually at the top of their favorites list but evidently a tasty meal all the same. They usually prefer shrubby Mugo Pines, but will attack other types of Pine as well. They appear at the same time as new growth (the "candles") on the pine trees, but do not attack the new growth. Instead they prefer to munch on last years needles. On heavily infested trees they can eat all of the old needles, leaving the tree with an unattractive "bottle brush" appearance. Their chewing can also cause the new candles to grow into a crooked "hook" shape, which is also not a desirable trait on an ornamental tree. On smaller trees where you can reach, they can be controlled by hand picking. When they are present in large numbers, control is important, especially on smaller trees because they can render a tree rather useless as an ornamental, and in rare cases they can kill the tree. Fortunately, they usually they don't.

Some pests really aren't pests at all, even if they do make a bit of a mess. A significant percentage of the bees you see flying around on Long Island aren't social bees (like the common honeybee) but are members of one of the many species of solitary "digger bees". You may notice places in the lawn or garden where they have bored pencil sized holes in the ground, sometimes in great numbers. Each hole contains the nest of a single bee (plus any offspring that are "raised" in the nest). The holes with small cones of dirt piled around the openings can be unsightly on a manicured lawn, but they won't harm the lawn. The digger bees are non-aggressive (considerably more so than social bees). Plus, they are important pollinators and you can think of the holes as free aeration.

Spring Cankerworms infest an Oak tree in Smithtown, May 2004:
Inch worms (spring cankerworms) defoliating an oak tree.  A neighboring Wild Cherry was already chewed completely bare.