INSECT DAMAGE TO SEEDS OF PACIFIC COAST CONIFERS. 3 



WORMY AND ABORTED CONES.' 



In some forms of injury the cone is not killed, but may show masses 

 of resin on the surface, castings caused by the feeding of larvse, or 

 little burrows through the scales, seed, and pith which contain small 

 larvse. In rare cases the cone may be aborted or deformed, forming 

 a peculiar growth or shape. The cone, however, continues to grow 

 and matures at the close of the season very much like a normal one. 

 The seeds which are not mined or eaten by the insects fill and mature. 

 Damage of this character may be found in practically all species of 

 conifers. Much of it is caused by the caterpillars of different species 

 of moths, some of which show nothing on the surface of the cone to 

 indicate their work in the interior. The amount of damage to the 

 seed of western yellow pine and Jeffrey pine throughout northern 

 California and southern Oregon in 1912 was estimated by the writer 

 to vary from 50 to 90 per cent of the crop. 



WORMY SEED.2 



This class of injury is found only in the seeds. The cone is not 

 affected and shows no indication of the insect. Practically all of the 

 reported damage of this type is caused by the larvse of tiny w^asps 

 called seed chalcidids. A certain percentage of the seeds will be 

 infested by a small, white, headless larva. The infested seeds are of 

 normal size and appearance. The larvse feed entirely within the 

 inner lining of the seed. Damage of this type can be found only by 

 cutting the seed. open. Seeds which have been attacked are hollow 

 and usually contain the small headless larvse of the chalcidid. After 

 the seed has been stored over winter some of the adults emerge, 

 boring small clean-cut holes through the outer shell of the seed. This 

 is the first external indication of these insects. Quite often seed 

 infested by the seed chalcidid is collected and sold before the infesta- 

 tion is detected. Injury of this type is very common in certain 

 species of fir, in which the damage has sometimes been found to run 

 as high as 75 to 90 per cent of the cleaned seed. Species of seed 

 chalcidids have also been found in the seed of western yellow pine 

 and Engelmann spruce. 



MAGGOTY CONES. 



Many cones are injured by the maggots of flies and midges, some of 

 which cause no appreciable damage to the seed. Small whitish or 

 pink-colored maggots are found in the cones of nearly all conifers. 

 They are the larvse of tiny gnats, or midges. The pinkish maggots 

 cause little masses of resin among the scales but do not seriously 

 affect the seeds. The whitish maggots in fir cones cause considerable 

 damage to both cone and seeds. (See PI. Ill, figs, a, c.) They are 

 often present in vast numbers and leave the cones when these are 



i PL I, fig. b 2 PI. Ill, figs. 6, d. 



