INSECT ENEMIES OF WESTERN FORESTS PHN 
The white fir cone maggot (Lonchaea viridana Meig.) 1s the com- 
mon white maggot found so abundantly in white fir and other bal- 
sam fir cones (fig. 8). These maggots mine through scales and 
seeds, often causing great damage. The larvae leave the cones as 
soon as they fall and form small ] puparia in the ground. Here they 
overwinter, and in the spring some of them emerge as small, black, 
shining flies. The great majority of the brood go through a 2- -year 
life cycle, emerging ‘the second spring after pupation. 
CONE BORERS 
The hard, dry cones of certain pines are frequently attacked by 
the larvae of flatheaded and roundheaded borers which riddle the 
interior and destroy the seeds. 
The roundheaded cone borer (Paratimia conicola Fisher) has the 
habit of boring tunnels through the hard pitch and scales of knob- 
cone pine cones. It works also in the dry limbs of the species. ‘The 
adults are a rusty reddish brown, and one-half inch in length. 
The flatheaded cone borer (Chrysophana placida Lec.) has been. 
found boring through the hard, dry cones of knobcone and_ponde- 
rosa pine. It also bores in the dead limbs, branches, trunks, and 
stumps of practically all western pines and firs. In the adult stage 
it is a small green or greenish-red beetle, about one-half inch in 
aes 
SEED CHALCIDS 
Seeds of many conifers are attacked by small wasps of the genus 
Megastigmus (71), which drill through the young green cones with 
their long evipositors and lay their eggs within the immature seeds 
(fig. 9). The small, white, legless larvae feed on and destroy the 
tissue within the seeds. The normal outer shell is formed later and 
shows no evidence on the surface that the seed is infested. The 
feeding habits of these insects are similar to those of the gall makers. 
In the following spring the larvae reach maturity and emerge as 
small yellow or nearly black wasps. Each adult leaves a smooth 
round emergence hole in the seed coat. Some hold over and emerge 
the second or even the third year. The damage by these seed-in- 
festing insects is an important factor in seed collecting, and often 
a high percentage of cleaned commercial seed will be found to have 
been ruined by these insects. 
There appears to be no practical means of preventing this damage; 
but to avoid the introduction of this insect into other countr les, in- 
fested seeds should be fumigated in a tight container with carbon 
disulphide. As this fumigant has a deleterious effect upon the ger- 
mination of the seed if used in excessive dosages, not more than 1 
ounce of fumigant should be used to 100 pounds of seed, and the 
fumigant should be completely removed by thoroughly aerating the 
seeds after they have been in the container for 48 hours. Carbon 
disulphide vapor mixed with air is explosive, and fire should be 
guarded against. Calcium cyanide may prove to be a more satis- 
factory fumigant, but which form of it should be used and how it 
affects the germination of seeds has not yet been fully determined. 
Since the gas evolved from calcium cyanide is a deadly poison this 
material should be used with caution, preferably by persons who 
have had experience with it. 
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