392 



INJURIOUS AND BENEFICIAL INSECTS OE CALIFORNIA. 



an army, devastating as they go. Like the grasshoppers, they attack 

 practically all kinds of plants, including field and truck crops, vine- 

 yards and orchards, as well as flowers and weeds. 



The eggs arc laid in the spring by the adults and the larvae become 

 exceedingly numerous in early summer, when most of the damage is 

 done. The pupal stage is passed underground ; the light or dark- 

 brown, naked chrysalids being housed in small earthen cells. There 

 are several broods a year. The winter is usually spent in the pupal 

 stage, but some adults also hibernate. 



Control. — The control of these insects has afforded difficult prob- 

 lems for years, and even today the methods worked out do not always 

 give ihe necessary relief. 



Fig. 392. — A light trap to catch moths of cutworms and 

 armyworms used by the American Sugar Beet Company at 

 Oxnard. Beneath the acetylene light is an oil pan into which 

 the moths fall and are destroyed. (After Weldon) 



Glean culture during the fall of the year and thorough plowing of 

 infested fields to kill the hibernating pupae in the cells is supposed 

 to greatly reduce the next year's broods. This has been recommended 

 as especially important in pea fields. 



When the worms begin to march, trenches may be plowed across 

 and ahead of their paths with a perpendicular wall in front of the 

 advance. The worms, not being able to cross, will gather in great 

 masses in these trendies and can he easily killed by spraying them 

 with crude oil or by crushing them with a narrow disk or roller. 

 Arsenical sprays applied as soon as the larva?, begin to appear will 

 sometimes materially aid in protecting crops like potatoes, tomatoes, 



