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



Key to Diagnosis of Insect Injury to Young Trees (Cont.) 



round, dirty lump of pitch and frass to 

 form at point of attack 



Pitch nodule moths, Petrova spp., p. 52 



(4) Small caterpillars, about 1/2 inch at ma- 



turity, bore through center of developing 

 shoots causing them to wither, droop, 

 and die. .Pine shoot moths, Eucosma spp., p. 52 

 Exoteleia spp., p. 52 



(5) Slender, grayish-white caterpillars, about 



3/8 inch long when mature, feeding on 

 bark of trunk or branches at forks or 

 points of injury, causing small exuda- 

 tion of resin mixed with frass and death 

 of affected part 



Bark moths, Laspeyresia spp., p. 53 



2. Leaves and buds at tips of branches killed. Trees often 



defoliated. Little or no damage to bark or wood. 



Bud moths, p. 54 



3. Tips of branches appearing unhealthy, sickly, badly swol- 



len and deformed, or killed. No borings under the bark 

 or in buds. 



a. Succulent tips covered with small, soft-bodied 



insects, or stems covered with powdery, cottony 

 incrustations or shell-like scales; trees dripping 

 a sticky exudation; often covered with a black 

 smut Sap-sucking insects, p. 55 



b. Terminal shoots or leaves enlarged, galled, or 



swollen Gall makers, p. 68 



c. Twigs with dying and dead needle tufts; bark 



filled with resinous pockets containing small red 

 maggots Pitch midges, p. 70 



INSECTS AFFECTING ROOTS 



Very few insects have been found attacking the roots of young 

 trees, but these few deserve mention. 



CARPENTER ANTS AND ROOT APHIDS 



Large black, or black and red, carpenter ants (Camponotus 

 spp.) from 1/4 to V2 inch long, commonly found building their 

 nests in logs, stumps, and houses (see p. 206), have been found 

 gnawing the outer bark and cambium of roots of young conifers 

 so that colonies of aphids (Cinara spp.) can feed on the fresh 

 wounds. This damage has caused the death of both planted and 

 wild seedlings in various parts of the Pacific Northwest. Cam- 

 ponotus herculeanus ligniperdus var. noveboracensis (Fitch) has 

 been found injuring and killing Douglas-fir and western hemlock 

 reproduction at several places in western Washington. The most 

 serious damage is done at the root collar of 4- to 8-year-old trees, 

 although older trees also are attacked. In southeastern Oregon 

 Camponotus herculeanus var. modoc Wheeler has been found doing 

 similar damage to small white firs and tending aphids (Cinara 

 curvipes (Patch)). These aphids have been found working on the 

 bark of white-fir twigs in California and Oregon. 



