18 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



Key to Diagnosis of Insect Injury to Cones and Seeds (Cont.) 



2. Cones reach full growth but are riddled with insect borings. 



a. Borings made by active caterpillars which leave pitchy 



masses of boring and excrement within the cone and 

 similar exudations at the point of entrance, or larval 

 mines in axis and mature seeds, without resinous 

 exudations Cone moths (p. 19) 



(1) Large reddish-green caterpillars throwing out 



webbed frass, with little or no pitch exud- 

 ing; pine, fir, and spruce cones 



Dioryctria spp. (p. 20, 22) 



(2) Similar caterpillars in cypress and Sitka 



spruce cones Heinrichia spp. (p. 23) 



(3) Similar work but caterpillars of "measuring 



worm" type Eupithecia spp. (p. 22) 



(4) Large white caterpillars, causing considerable 



pitch flow and resinous masses in fir cones 



Barbara spp. (p. 21) 



(5) Small pink or gray-white caterpillars with 



black heads boring within silken-lined tun- 

 nels mostly through axis of cones and into 

 the seeds Laspeyresia spp. (p. 20, 22) 



(6) Small white or pink caterpillars boring 



through pine cone scales. . . .Eucosma spp. (p. 20) 



b. Chewing by slugs on fresh cones of incense cedar 



Incense cedar sawfly (p. 23) 



c. Soft fir cones riddled by small, white, slim, maggots 



which leave fine excrement in tunnels, but free from 

 masses of pitch Cone maggots (p. 23) 



B. Old, persistent, hard, dry pine cones mined by slender, white, 



roundheaded or flatheaded larvae Cone borers (p. 23) 



C. Insects attacking coniferous seeds only. 



1. Seeds show no external injury, but contain small, white, 



curled, legless grubs in interior cavity Seed chalcids (p. 24) 



2. Seeds swollen and galled, containing small, pink maggots 



Seed midges (p. 23) 



D. Injuries to nuts or seeds of broad-leaved trees. 



1. Seeds, nuts, or acorns showing no external injury but mined 



by small, white, curled, legless grubs. 



a. In oak acorns and hazel nuts Acorn weevils (p. 26) 



b. In ash seeds Ash-seed weevil (p. 26) 



c. In mesquite, acacia, horsebean, catclaw, palo-verde, 



and locust Bean weevils (p. 27) 



2. Interior of seeds or acorns mined by active caterpillars 



which discharge webbed frass through exit hole. 



a. In oak acorns and hazel nuts Filbertworm (p. 26) 



b. In maple Maple seed caterpillar (p. 26) 



CONE BEETLES 



Pine cones that dry and wither before they are half grown, 

 and either drop to the ground or are retained as blighted imma- 

 ture specimens, usually have been killed by the cone beetles 

 (Conophthorns spp.) (116). 



The adults are small, dark, shining cylindrical beetles, from y 16 

 to % 2 inch in length. They bore into the base or supporting stem 

 of the immature pine cones in the spring soon after the beginning 

 of the second year's growth. A small tunnel is projected through 

 the axis of the cone, and in this the female beetle deposits her 

 eggs. From these hatch small, white, curled, legless grubs, which 

 feed on the scales, seeds, and tissues of the withering cone. Devel- 

 opment to the adult stage is completed during the summer within 



