INSECT ENEMIES OF WESTERN FORESTS 53 
KEY TO THE RECOGNITION OF SOME IMPORTANT INSECT GALLS 
A. Galls formed on coniferous trees. 
1. Galls affecting pine needles. 
a. Needles greatly enlarged or swollen at the base 
gall midges, page 538. 
b. Needles blistered within the sheaths, causing pre- 
MAcuUreySHedCINne= =a se pine needle mite, page 52. 
2. Twigs with dying and dead needle tufts; bark filled with res- 
inous pockets containing small red maggots 
pitch midges, page 54 
3. Swollen twigs of western white pine covered with gray, cot- 
OM Vs SCCTEGlONE He ey. Na ee woolly pine louse, page 48. 
4. Cone-shaped galls on terminal twigs of spruce 
spruce gall bark lice, page 47. 
5. Prickly, burrlike or conical galls on juniper___ gall midges, page 53. 
B. Galls formed on broadleaved trees. 
1. Galls inhabited by small, white, legless, apparently headless 
i 2s Vise Care eer hein an ee EL TAS Tap CS ile cynipid wasps, page 53. 
2. Galls inhabited by small pink or red maggots__ gall midges, page 53. 
3. Galls inhabited by small bugs with cottony wax secretions 
gall aphids, page 47. 
4. Galls inhabited by microscopic eight-legged mites 
gall mites, page 52. 
GALLFLIES OR CYNIPID WASPS 
(Cynipidae) 
One group of small, four-winged, usually somber-colored yellow to 
brown or black, antlike wasps are responsible for the formation of a 
great variety of galls on the different parts of various forest trees, 
but particuarly on the oaks. These galls may be large, round, and 
shiny, like the common oak apples, or very irregular in shape and 
spiny, or may consist of just a tiny swelling on. leaf, twig, or root. 
The larvae that inhabit these galls are white, legless, and without 
a distinct head. There are over 200 species described from various 
plants in the Western States. Only a few, however, do any appre- 
ciable damage. 
GALL MIDGES 
The gall midges belonging to the family Cecidomylidae are re- 
sponsible for the formation of a great variety of small galls on many 
different forest trees and plants. The adults are tiny pink flies re- 
sembling mosquitoes and are called midges. The larvae are small 
pink or red maggots, without legs or definite head, but with a dark 
“breastbone.” Almost any part of the tree may be affected, but most 
galls are formed on the needles or leaves, in the cones or seeds, or in 
the bark of twigs. A few species on forest trees are of some economic 
importance. 
The Monterey pine midge (Vhecodiplosis pini-radiatae S. and M.) 
works at the base of the newly formed needles of Monterey pine in 
central California and causes them to become swollen and shortened 
(fig. 24). Sometimes heavily infested twigs are killed and the orna- 
mental value of the trees seriously impaired. Other species that 
produce swellings at the base of needles on pines include /anetiella 
coloradensis Felt on pines in Colorado and Utah, and 7'hecodiplosis 
cockerellt Felt on Pinus edulis in Colorado. 
a eee 
