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



ally all western pines and firs. The adult is a small green or 

 greenish-red beetle, about 1/2 inch long. The roundheaded borer 

 (Phymatodes nitidus Lee.) is frequently found in redwood cones. 



#i 



Figure 8. — White fir cone maggots (Lonchaea viridana) , commonly destruc- 

 tive to seeds of white fir. X 2. 



SEED CHALCIDS 



Seeds of many conifers are attacked by small wasps of the genus 

 Megastigmus (123), which drill through the young green cones 

 with their long ovipositors and lay their eggs within the immature 

 seeds (117) (fig. 9). The small, white, legless larvae feed on and 

 destroy the tissue within the seeds. The normal outer shell is 

 formed later and the surface shows no evidence 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 ma- 

 turity and adults 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-infesting 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 damage 

 by seed chalcids. If seeds are to be shipped to other countries, it 

 may be desirable to fumigate them before shipment. Any of the 

 common grain fumigants may be used. These fumigants will not 

 injure germination, provided the moisture content of the seed is 

 not over 12 percent and exposures are limited to 24 hours. Recom- 

 mended dosages per 1,000 bushels of seed are 15 pounds of cal- 



