. The cultivated evergreens; a handbook of the coniferous and most important broad-leaved evergreens planted for ornament in the United States and Canada. Evergreens; Conifers. INSECTS, DISEASES, AND INJURIES 131 The pitch-mass borer (Parharmonia pini, Kellicott). The trunks of healthy pine trees are often disfigured by large unsightly masses of gum, caused by the larvae of a beau- tiful, blue-black and orange, narrow-winged moth which burrows in the inner bark and sapwood. The insect sometimes requires three years to complete its development. It may be held in check by carefully removing the
. The cultivated evergreens; a handbook of the coniferous and most important broad-leaved evergreens planted for ornament in the United States and Canada. Evergreens; Conifers. INSECTS, DISEASES, AND INJURIES 131 The pitch-mass borer (Parharmonia pini, Kellicott). The trunks of healthy pine trees are often disfigured by large unsightly masses of gum, caused by the larvae of a beau- tiful, blue-black and orange, narrow-winged moth which burrows in the inner bark and sapwood. The insect sometimes requires three years to complete its development. It may be held in check by carefully removing the mass of pitch and killing the borer in its burrow. Spruce gall aphid (Chermes ahietis, L.). Figs. 14, 15. Norway and white spruces are subject to attack by a plant-louse which causes the formation of cone-shaped galls at the base of the smaller twigs. These galls are about one inch long and bear a striking resemblance to a small pineapple. The infested twigs may die, and when the galls are numerous the tree may assume a ragged and unsightly appearance. Young trees are most liable to serious injury. The plant-louse which produces the galls lives over winter in a partly grown condition, hidden away in cracks of the bark around the buds. In the spring these aphids complete their growth and about the middle of May de- posit a cluster of ap- proximately three hundred yellowish eggs. These eggs hatch in about a week and the h. Work of spruce gall aphid—C/termcs Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bailey, L. H. (Liberty Hyde), 1858-1954. New York, The Macmillan company; London, Macmillan & co. , ltd.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectconifer, bookyear1923
