Forest Pests: Insects, Diseases & Other Damage Agents

Introduction

Maier, C.T., C.R. Lemmon, J.M. Fengler, D.F. Schweitzer, and R.C. Reardon. 2004. Caterpillars on the Foliage of Conifers in the Northeastern United States. FHTET-2004-1. Morgantown, WV: USDA Forest Service, Forest Health Technology Enterprise Team; 151 p.

Coniferous forests are important features of the North American landscape. In the Northeast, balsam fir, spruces, or even pines may dominate in the more northern forests. Southward, conifers still may be prevalent, with the pines becoming increasingly important. In dry, sandy areas, such as Cape Cod of Massachusetts and the Pine Barrens of New Jersey, hard pines abound in forests composed of relatively small trees. Conifers are classic symbols of survival in harsh environments.

Forests of conifers provide not only beautiful scenery, but also livelihood for people. Coniferous trees are a major source of lumber for the building industry. Their wood can be processed to make paper, packing material, wood chips, fence posts, and other products. Certain conifers are cultivated for landscape plants and, of course, Christmas trees. Trees of coniferous forests also supply shelter or food for many species of vertebrates, invertebrates, and even plants. Insects that call these forests home far outnumber other animals and plants.

Because coniferous forests tend to be dominated by one to a few species of trees, they are especially susceptible to injury during outbreaks of insects such as the spruce budworm, Choristoneura fumiferana, the fall hemlock looper, Lambdina fiscellaria fiscellaria, or the pitch pine looper, Lambdina pellucidaria. Trees that are defoliated by insects suffer reduced growth and sometimes even death.

Trees stressed by defoliation, drought, or mechanical injury, generally are more susceptible to attack by wood-boring beetles, diseases, and other organisms. These secondary pests also may kill trees. Stress or tree death can have a negative economic impact upon forest industries. In addition, severe injury has other, often less obvious, impacts on the health and the inhabitants of forests. For example, defoliation can destroy the food and the habitat of insects and other animals, causing their decline or possibly extirpation.

Most caterpillars and other insects, however, are not pests. Many provide essential food for animals and plants, recycle nutrients, or destroy noxious insects and plants. Furthermore, studies of forest insects have been instrumental in developing the fields of ecology, animal behavior, and environmental health.

In this manual, we furnish descriptions and photographs of caterpillars, as well as information on life history, to assist foresters, extension agents, educators, students, conservationists, and others who wish to identify and understand the caterpillars that eat the foliage of conifers.

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