INSECTS INJURIOUS TO ORCHARD FRUITS 495 



ment. Characteristic light reddish hairs are scattered over the 

 pupa. The pupal stage lasts from ten days to two weeks, 

 when the adult emerges. The moths emerge from the middle 

 of July to late August. The male is brownish-yellow, varying 

 to greenish-brown in color, the wings being marked with darker 

 stripes, has a slender body and the wings expand about 1 J inches. 

 It flies by day with a peculiar zig-zag flight. The female moth 

 is nearly white with numerous small black markings, is heavy- 

 bodied and sluggish. The wings expand about 2 inches, but 

 fortunately the female is unable to use them for flight. Were it 

 not for this the spread of the pest would have been much more 

 rapid. After mating the moths live but a short time and do 

 no damage. 



The pest is spread mostly in the caterpillar stage The young 

 caterpillars drop down on fine silken threads and may alight on 

 vehicles which transport them to non-infested areas. When just 

 hatched, the caterpillars have very long hairs, slightly expanded 

 at the base, and these, with the silk which they spin out, serve 

 to buoy them up in the air so that they may be carried for a 

 considerable distance by a strong wind Where they occur in 

 myriads on high trees, the little caterpillars may be carried by 

 the wind for considerable distances, and this is one of the chief 

 means of spread.* The egg masses may also be transported on 

 merchandise or boxing, and the pest has undoubtedly become 

 established in several localities in this way. A few cases of 

 importation on nursery stock have been known 



The caterpillars will attack any of the fruit, shade or wood- 

 land trees, and where they become excessively . abundant will 

 destroy all green vegetation of almost any kind. It is essentially 

 a pest of forest trees, but where it occurs it defoliates all of the 

 common fruit trees. Coniferous trees are killed after being once 

 stripped of their foliage, and deciduous trees usually die after four 

 or five defoliations. Recent experiments show that the young 

 caterpillars when they hatch from the eggs are unable to feed on 

 conifers, so that growths of soft wood may be protected by keep- 

 ing all hard-wood trees cut out 



* See C. W Collins, Bulletin 273, U. S Dept. Agr. 



