118 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



needles, leaves, or shoots. The eggs hatch in about a week, and 

 feeding starts on the foliage. Feeding is completed by midsummer, 

 and the slugs drop to the ground to prepare for transformation, 

 usually spinning the tough papery cocoons. Other species pass the 

 winter in the eggs, which hatch early in the spring, the larvae 

 completing their feeding and transformation by fall, at which time 

 flight and egg laying again take place. 



The native sawflies are attacked by numerous parasites that 

 play an important part in holding them in check, but weather con- 

 ditions seem to be even more important in determining the number 

 of sawflies in different seasons. 



Direct control can be effected where it is practical to apply DDT 

 or arsenical poisons, such as on shade and ornamental trees, or to 

 forest areas by means of airplanes. Usually, however, the cost of 

 control is not justified, because of the expense, the difficulty of 

 applying sprays, and the fact that most outbreaks are rather 

 quickly suppressed by natural control agencies. 



In the forests of western North America there are numerous 

 native species of sawflies, which, although usually inconspicuous 

 in numbers, may periodically become prevalent enough to cause 

 noticeable damage. So far, although extensive defoliations have 

 occurred, the actual destruction of timber has been small, and the 

 outbreaks have quickly subsided. 



SAWFLIES ON CONIFERS 



A number of species of sawflies belonging to several genera 

 attack the needles of pines and other conifers. The adults are col- 

 ored variously, often black or brown, and with yellowish appen- 

 dages. They are usually from 2 4 to 1 2 inch long. The males fre- 

 quently have large, feathery antennae while those of the females 

 are threadlike. Eggs are laid singly, in slits made in the needles. 



The young hairless larvae first feed in clusters on the nearest 

 needles, then as they grow they scatter out over the foliage and 

 feed singly. Upon reaching full growth, about the first of Septem- 

 ber, they are from y 2 to 1 inch long, usually greenish, with black 

 or brown heads, and have eight pairs of prolegs. Upon completing 

 their feeding they usually drop to the ground and form brown, 

 papery cocoons in the forest debris, but some may form cocoons on 

 the needles or in crevices of the bark, while still others do not 

 construct cocoons. The winter is usually passed in the prepupal, 

 larval, or egg stage, and the new adults emerge the following- 

 spring. These sawflies are easily controlled where trees can be 

 sprayed with DDT, lead arsenate, or other stomach poison. 



The lodgepole sawfly (Xeodiprion burkei Midd.) (fig. 53), in 

 the adult stage, is about 1 3 inch long. The males are black and the 

 females brownish. The hairless, wrinkled bodies of the larvae are 

 greenish or grayish, with lighter lateral and dorsal stripes, brown 



