INSECT ENEMIES OF WESTERN FORESTS 31 



or as pupae in earthen cells. Emergence takes place the following 

 spring. Some species may have several broods a year. 



Clean culture in the nursery to avoid the establishment of weeds 

 or ground cover that would be suitable for egg laying, and culti- 

 vation in the fall and winter to destroy the hibernating larvae, 

 will do much to prevent cutworm damage. Where such methods 

 fail, commercially prepared poison baits scattered over the beds 

 just before dusk are effective, or the beds may be dusted with 

 cryolite or DDT. 



MAGGOTS 



The seed-corn maggot (Hylemya cilicrura (Rond.)) is a com- 

 mon pest of various farm crops, but is comparatively rare in for- 

 est nurseries. It has been reported from forest nurseries in the 

 East, but in the West has been found only in one nursery at Nis- 

 qually, Wash., where 40 to 50 percent of Douglas-fir seedlings 

 were lost in 1944 because of its injury. Spruce seedlings were also 

 attacked. 



The seed-corn maggot passes the winter in the prepupal or 

 pupal stage within a brown puparium, about the size of a grain 

 of wheat, at a depth of 6 to 7 inches in the soil. In April the ash- 

 gray flies, about % 6 inch long, with the two wings folded back so 

 the outer edges are nearly parallel, emerge and lay their eggs in 

 the soil just as the ground begins to crack above the germinating 

 seed. The soft-bodied, yellowish-white, legless maggots burrow 

 through and beneath the thin bark of the stem and feed up to a 

 short distance above the ground and down into the roots. The 

 maggots are approximately y 4 inch long when full grown. Maxi- 

 mum damage is done early in the spring on cold, wet sites where 

 the soil has an abundance of organic matter. Adults emerge late 

 in July or early in August. There are two generations a year. 



The following methods of control have been proposed : 



(1) Delaying planting to avoid the cold, wet period most favor- 



able for egg laying. 



(2) Applying a DDT spray (2 pounds of 50-percent wettable 



powder to 100 gallons of water) at the rate of 2% gal- 

 lons per 1,000 square feet of seed bed, just as the ground 

 begins to crack above the germinating seed, to prevent 

 egg laying. 



(3) Applying an inorganic fertilizer in the fall prior to plant- 



ing or after the seedlings are 1% to 2 inches above 

 ground. 



(4) Fumigating the soil before planting with carbon bisulfide 



(1 quart of 50-percent miscible to 50 gallons of water) 

 at the rate of 1 pint per square foot, or with D-D mixture 

 or ethylene dibromide at the rates given for control of 

 wireworms (p. 30). 



SYMPHYLIDS 



Symphylids, or garden centipedes, are slender, white, active 

 creatures about i/ 4 inch long. They thrive in damp soil with abun- 



