INSECTS AFFECTING FIELD CROPS 497 



saturated with it, should be placed on top of the grain. As 

 the gas that comes from it is heavy it will sink and reach all 

 parts of the bin. Remember that this gas is inflammable and 

 explosive. If the grain in the bins can be heated to 120 F. all 

 the weevils in all stages of development will be killed. 



The Saw-toothed Grain-beetle (Silvanus surinamensis). 

 Unlike the weevils, which are somewhat cylindrical, this small 

 grain-beetle is quite flat. It may easily be recognized by the 

 serrate margins of the prothorax. The larvae are long and 

 slender and provided with six 

 legs, enabling them to move 

 about freely and thus injure 

 several grains. The methods 

 of control are the same as for 

 the weevils. 



The Angumois Grain-moth 

 (Sitotroga cerealella) . In the 

 south the grain-moth is even 

 a worse pest than the weevils 

 for it often occurs in almost 

 incredible numbers and attacks 

 wheat in the field as well as in 

 the granaries. The moths fly 

 from the storerooms while the 

 wheat is heading, and lay their eggs on the grain. The larvae 

 make their way into the kernels and become full grown about 

 the time the wheat is mature. Other generations follow, 

 the members of each attacking the grain wherever it is 

 found, in the field, in the stack, or in store-rooms. Corn is 

 not attacked as often as wheat, but seed corn stored in barns 

 may often be badly injured. The grain should be threshed 

 as early as possible and stored in tight bins or good sacks. If 

 it becomes infested while stored, it may be treated with car- 

 bon bisulphide. Cleanliness about the barns and particularly 

 around the granaries is most essential. Badly infested grain 

 may be fed to chickens or hogs. 



The Mediterranean Flour-moth (Ephestia kuehniella) . 

 Mills are sometimes overrun with the larvae of a small grayish 



FIG. 234. Adult, pupa, and 

 larva, of the saw-toothed grain- 

 beetle, Silvanus surinamensis. 

 (Much enlarged; after Howard and 

 Marlatt.) 



