IMPORTANT NORTH AMERICAN FOREST INSECTS 21 



THE TENT CATERPILLARS 



Malacosoma disstria Hiibn. 



Malacosoma americana Fab. 

 Malacosoma californica Pack. 

 Malacosoma constricta Stretch 



Malacosama pluuialis Dyar 



Malacosoma fragilis Stretch 



The tent caterpillars are frequently important forest defoliators 

 as well as farm and orchard pests. They have a wide range of host 

 plants. Some species are widely distributed over the United States, 

 whereas others are rather restricted in distribution. A recent in- 

 festation on the Carson National Forest in New Mexico spread 

 fiom 10 sections in 1926 to approximately 225 sections in 1929 (23, 



THE PINE BUTTERFLY 



Xeophasia menapia Felder 



At irregular periods large areas of western yellow pine, western 

 white pine, and lodgepole pine are defoliated in Idaho, Montana, 

 and the Pacific Coast States by caterpillars of the pine butterfly. 

 Death of the trees through loss of the needles or attack by bark 

 beetles follows severe defoliation (24). 



THE HEMLOCK BUDWORM 



Peronea variana Fern. 



The hemlock budworm, as recognized at present, occurs in the 

 northeastern part of the United States and Canada as well as in the 

 Pacific Xorthwest, British Columbia, and Alaska. At times it is 

 extremely destructive over wide areas, feeding chiefly on hemlock, 

 although the spruces and firs are also attacked. At present active 

 outbreaks occur along the St. Lawrence River in the eastern part of 

 Canada and on the Olympic peninsula on the Pacific Coast. Little 

 is known of its habits. 



THE GIPSY MOTH 



Poi'thetria dtepar L. 



The control of the gipsy moth is a problem in the care of shade, 

 park, and forest trees in the Xew England States. The nearly om- 

 nivorous feeding habits of the larvae of this insect and the methods 

 of pupation and egg laying have rendered it a pest exceptionally 

 difficult to control. It has killed many trees, particularly oaks, in 

 the infested area (12). 



THE CALIFORNIA OAK WORM 



Phryganidia californica Pack. 



Considerable areas of oaks on the Pacific coast are frequently de- 

 foliated by the caterpillars of the California oak moth. This species 

 is at times sufficiently abundant and injurious to demand control 

 measures (11). 



