. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 42 THE SCOLYTID BEETLES. No. 1. THE WESTERN PINE BEETLE. {Dendroctonus brevicomis Lee. Figs. 6-1L) The western pine beetle is a rather stout, brownish, cylindrical bark- beetle, from 3 to 5 mm. in length, with head broad and grooved, pronotum punctured and but slightly narrowed toward the head, and elytra with fine rugosities, but entirely without long hairs. (See fig. 6.) It attacks healthy, injured, and felled western yellow pine and sugar pine, and is destructive to living timber in the moun- tains of Californ
. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 42 THE SCOLYTID BEETLES. No. 1. THE WESTERN PINE BEETLE. {Dendroctonus brevicomis Lee. Figs. 6-1L) The western pine beetle is a rather stout, brownish, cylindrical bark- beetle, from 3 to 5 mm. in length, with head broad and grooved, pronotum punctured and but slightly narrowed toward the head, and elytra with fine rugosities, but entirely without long hairs. (See fig. 6.) It attacks healthy, injured, and felled western yellow pine and sugar pine, and is destructive to living timber in the moun- tains of California and northward and eastward to Washington and Montana. The adults excavate long, winding egg galleries (fig. 7), through the inner layers of living and dying bark. The white, legless larvae hatching from the eggs excavate short larval mines in the middle portion of the inner bark, the latter rarely showing on. Fig. 6.—The western pine beetle (Dendroctonus brevicomis): Adult, larva, pupa, greatly enlarged. (Adult and larva, author's illustrations; pupa, from Webb.) the inner surface. Later they transform to pupse and adults in the outer corky bark. Pitch tubes (figs. 8, 9) are produced on the main trunk of the living trees attacked. The fading to yellowish and reddish foliage indicates its destructive work. SEASONAL HISTORY. OVERWINTERING STAGES. The broods pass the winter in the outer bark of trees attacked the preceding late summer and fall, as parent adults, young adults in pupal cases, all stages of larvae, and possibly pupa?. ACTIVITY OF OVERWINTERED BROODS. The overwintered parent adults extend their galleries or excavate new ones and deposit eggs during April and May, from which broods develop and emerge by the last of July to the middle of 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 U
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