Riddle: What creature, scarcely an inch in length, can defoliate more of the north woods than logging and forest fires combined?

Answer: The spruce budworm.

It is the larval stage (the worm, not the adult moth) that kills trees. Hatching from tiny eggs that typically are fastened to the underside of a spruce needle, the larvae spin themselves a hammock and hide out for the winter. With the arrival of warm weather in May, they emerge and progress through a series of stages called instars. They start by eating last yearís needles and unopened buds. When the buds expand and shoots start to grow out, the worms are ready. Spinning silken threads across the shoots, the worms pull needles together in a ìfeeding tubeî configured to make it easy for the worms to graze. While feeding, the worm clips off the growing needle at the base, leaving the remainder to hang and turn brown in the silky thread of the feeding tube.

This happens at such a small scale that unless you have seen it first hand, you can hardly imagine the vast destruction that results. Riding down the river in a boat, you will see mile after mile of brown woods. You would think it must be mid-winter.

The trees attempt a second growth, but in bad years the worms take this as well. Trees are tough, surviving this treatment for a year or two. If the worms are around long enough, however the outcome is not in doubt. Even if defoliation does not directly kill, it so weakens the trees that they cannot resist disease or even mild drought.

We have spent seven summers trying to clear away the wreckage of this infestation. The Canadian Forest Service is at work developing a biological agent to control budworm outbreaks. This agent could take the place of hazardous insecticides that today are the only available protection. We will never be able to test such a solution through the thousand ramifications that come with a complex natural food chain, but the damage of the budworm is too extensive for Canadian forestry to ignore.

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Forest Lake Times
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880 SW 15 St.
Forest Lake, MN 55025
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