Cone beetles : injury to sugar pine and western yellow pine /

Abstract

A class of damage which has been termed " blighted cones " occurs frequently in the seed crops of sugar pine throughout its range in California and Oregon and of western yellow pine in the Pacific coast and southern Rocky Mountain regions. This damage is distinguished by the dying of the immature cones soon after the starting of the second year's growth. The dead blighted cones, which are less than one-half the size of normal cones, are withered and faded to a reddish brown. The blighted sugar-pine cones fall to the ground during the first summer, whereas the blighted yellow-pine cones may adhere to the branches for several }^ears. INSECTS CAUSING DAMAGE. The greater part of this damage 1 is caused by small scolytid beetles, which have been identified by Dr. A. D. Hopkins, of the Bureau of Entomology, as Conophthorus spp. The common name of " cone beetles " seems most appropriate for these insects, as their life history and the damage caused by them relate entirely to the cones of the host trees. The adults are small, black, cylindrical beetles, from 3 to 4 mm. in length. The adult beetle bores a small tunnel through the axis of the cone, wherein the eggs are deposited. The larvae, tiny white grubs from 3.5 to 4.5 mm. in length when full grown, feed upon the scales, seeds, and tissues of the withering cone. The pupae, which differ but little in size and color from the larvae but possess the form of the adult, are formed within the same cone 1 The caterpillars of certain cone^moths also kill immature second-year yellow-pine cones, in such a way that the damage resembles the work of the cone beetle, but this damage may be readily recognized by the character of the attack. In the areas observed by the writer the cone worms cause less than 10 per cent of the blighted cones. Note.-This bulletin is the result of field observations made in Oregon and California. It is suitable for distribution on the Pacific coast.

Insects Affecting Seed Production in Red Pine: Part I Conophthorus resinosae Hopk. (Coleoptera: Scolytidae)

“…Parasitism and disease, although important in some Conophthoncs species (9,17) were found negligible in C. resi~~oscre. During rhe presrnr investigation, no mortality of the insect in cones could be attributed to p a r a s i~m or disease, although two adults of B~a c o a rhy~cioniue (Mues.)…”

“…C. Im~rhertimae in sugar pine (17), and often C. co?zi.perd~~a in white pine cones. In cones with a long petiole, the beetle enters through a tunnel started in the petiole, .e.g.…”

“…Miller (17) shows photographs of the C. ponderosae tunnel in ponherosa pine cones, in which it seems that the parent adults of this species also leave via the entrance tunnel, but this is not stated specifically in the rext, After completion of attack in cones oh sugar pine and white pine, respectively, adults of C. Imbertianae and C. coniperda bore out through the distal end of the cone (17,23). C. resinosae adults leave the red pine cone via the entrance tunnel, as prevjouslv described.…”

“…The phenomenon of extended dormancy which has been reported for some cone insects (16,24), does not occur in C. ponderosae and C. lmbertianae (17), or in C. resinosae, although Chamberlin (3) states that some Conophthorus species (( . .…”

“…Miller's study of Pacific coast cone insects (16,17) deals with C, ponderosl~e Hopk. Miller's study of Pacific coast cone insects (16,17) deals with C, ponderosl~e Hopk.…”