HANDBOOK OX IXSECT ENEMIES OF FLOWERS AND SHRUBS 85 



These galls occur on blue, Engelmann, 

 and Sitka spruces in both the West and 

 the East. The infested tips are killed, 

 and the trees may thus be deformed. 

 This tiny aphid has a more complicated 

 life cycle than the preceding species, 

 spending part of its cycle on spruce and 

 part on Douglas fir' On spruce the 

 young hibernate near the buds, and the 

 galls are formed in the spring in the 

 same manner as those of the eastern 

 spruce gall aphid (see p 84). The galls 

 open in July, and the winged aphids 

 migrate to Douglas fir, where they lay 

 groups of eggs on the needles. The 

 young overwinter, mature in the spring, 

 and become covered with a white cot- 

 tony excretion. They appear as tiny 

 bits of cotton on Douglas fir needles. 

 These produce a summer generation, 

 and some of the adults fly to the spruce 

 trees, whereas others remain on the 

 fir. Some injury may result to the fir 

 needles from the sucking of these in- 

 sects. 



Figure 144. — Gall of Cooley's spruce 

 gall aphid at the tip of a new-growth 

 shoot. About two-thirds natural size. 



Treatment. — Same as for the eastern 

 spruce gall aphid. However, with this 

 species both the spruce and Douglas 

 fir should be sprayed thoroughly. The 

 planting together of the above-men- 

 tioned spruces and Douglas fir should 

 be avoided. 



Spruce Spider Mite 



Spruce trees, especially blue spruce, in- 

 fested with the spruce spider mite (Para- 

 tetranychus unanguis (Jacobi)) have a 

 rusty and unthrifty appearance due to 

 the sucking of the juices by the mites 

 and the accumulation of the webbing 

 which they spin abundantly (fig. 145). 



^^& 



Figure 145. — Mottling and webbing of 

 hemlock foliage by a spider mite. 



Similar injury may occasionally be caused 

 by the two-spotted spider mite (pp. 11, 

 42). Older needles are first attacked, 

 and injury is usually first noticed on 

 the lower branches. When young trees 

 are severely attacked they become badly 

 stunted or may even die the first season. 

 In older trees the killing is progressive 

 and death will result after a few years 

 of attack. Arbovitae, cedar, hemlock, 

 and certain pines are also attacked. 

 This mite is particularly injurious and 

 abundant during hot, dry seasons and 

 is often most serious in spring and fall. 

 It resembles the common red spider, 

 the young being pale green, and the 

 adults dark green or nearly black. The 

 mite passes the winter as spherelike eggs 

 laid at the bases of the needles. The 

 young mites hatch early in spring, and 

 several generations occur during the 

 season. 



Treatment. — Same as for the red 

 spider (p. 11). Application should be 

 made as soon as growth starts in the 

 spring, to control early infestations. 



Spruce Budworm 



On ornamental spruces and other 

 conifers the caterpillars of the spruce 

 budworm (Ar chips fumiferana (Clem.)) 

 feed bV boring into the opening buds and, 

 later on, the needles, which are cut off 

 and held together with silken threads 

 (fig. 146). The beauty of the trees is 

 temporarily spoiled because as the 

 needles dry they turn brownish. Heavy 

 feeding results in a stunted growth, 

 especially in the tops. While this 

 budworm is primarily a pesl of forest 



