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



it is not particularly destructive, but from 1921 to 1925, working 

 in conjunction with the lodgepole sawfly (Neodiprion biirkei 

 Midd.) (p. 118), it destroyed trees over a large area of immature 

 lodgepole pine near West Yellowstone, in Montana. Since the 

 cessation of the sawfly epidemic the pine tube moth is still present 

 in many areas, but has ceased to be destructive. 



The adult is a small brownish-gray moth with darker 

 patches and bands on the f orewings and a wing expanse of about 

 y 2 inch. Eggs are laid during the latter part of June and early in 

 July in groups of 2 to 30, with an average of about 10 per cluster, 

 on the concave side of lodgepole pine needles. These eggs hatch in 

 7 to 10 days, and the young larvae crawl over the foliage until 

 needles satisfactory for their attack are found — usually those of 

 the current year's growth. Each larva then enters a needle by 

 biting a circular hole near the tip and spends from 2 to 3 weeks in 

 feeding on the interior tissues. The inside of the mined needle is 

 lined with a papery, white, closely woven web to form a tube. At 

 an early period in the growth of the larva or when it becomes too 

 large for the mined needle, several other needles are drawn to it 

 and bound together so as to form a new and larger tube (fig. 41, 

 B) . This tube is also lined with a papery white web and has an 

 opening at each end, that allows the insect to leave quickly when 

 disturbed. Often a caterpillar will abandon one tube and form a 

 new one. Feeding takes place within the tube, and as the cater- 

 pillar becomes larger the tube is extended farther down the 

 needles, often to the base. During the latter part of August the 

 mature caterpillar, which is dark green and about y 2 mcn long, 

 drops to the ground on a silken thread and, after crawling into the 

 mat of old needles, spins a loosely woven cocoon in which it passes 

 the winter in the pupal stage. The adult emerges the following 

 May or June, completing one single annual generation. The work 

 of the pine tube moth is recognized by the silk-lined tubes, which 

 may consist of as many as 16 needles webbed together, and which, 

 as a result of the feeding, turn brown and die. 



The orange tortrix {Argijrotaenia citrana Fern.) in the larval 

 stage feeds at the base of needles on terminal and lateral buds of 

 Monterey pine in California. The adults are small tan-to-brown 

 moths. 



The spruce bud moth (Zeiraphera ratzeburgiana Sax.) is an in- 

 troduced pest that has become established in the Pacific Northwest 

 and Alaska. The small, light-brown moths, with darker diagonal 

 markings, and a wing expanse of about y 2 inch, lay their eggs on 

 spruce needles. Each young caterpillar crawls into an opening bud 

 and feeds on the tender new needles, webbing them together to 

 form a shelter, within which it feeds. Growth is completed late in 

 the summer, when the larvae reach a length of % inch, and the 

 chrysalis is formed in the shelter at the tip of the infested twig. 

 The adults emerge late in the summer. There appears to be one 

 generation a year. The damage has been frequently noted on young 

 Sitka spruce trees along the coast of Oregon and Washington. On 

 many trees all the new tips are killed and the tree is made to 



