350 



MILL AND ELEVATOR INSECTS 



creeps into cracks filled with flour or other inaccessible places, 

 escaping the fumes of gas which are successfully used against 

 other mill pests. In a high temperature it is capable of under- 

 going its entire life cycle in a little over a month. There are prob- 

 ably four broods a year in well-heated buildings (Fig. 358). 



Injury. It is practically omnivorous. Besides grain and its 

 products, it attacks snuff, baking powder, rice, ginger, slippery 

 elm, red pepper, beans, peas, nuts, and seeds of various kinds. 

 It also becomes a serious museum pest by invading cabinets of 

 dried insects. It is a most important flour pest. 



Control. Fumigation with hydrocyanic acid gas is practically 



the only effective remedy, and 

 that is not always successful, for 

 reasons given above. (See page 

 353 for fumigation methods.) 



The Yellow Meal Worm. 

 This beetle (Tenebrio molitor 

 Linn.), nearly black in color, is 

 flattened, shining, and over 

 one-half of an inch long. It 

 resembles on a large scale one 

 of the flour beetles. The larva 

 is cylindrical, about one inch 

 long, with a waxy appearance, 

 somewhat like a wire worm. 

 It is yellowish in color. The 



FIG. 357. Silken tubes covered with . ., , , 



wheat made by larvae of the meal snout moth; posterior extremity terminates 



in two small spines (Fig. 359). 



The beetle deposits her eggs in meal or in other substances, and 

 the grubs, after hatching, eat the substance in which they find 

 themselves. Two weeks are required for eggs to hatch, and 

 three months pass before the larva or grub becomes full grown. 

 One brood a year occurs. These beetles are fair flyers and are 

 nocturnal in their habits; they are often attracted to lights. 



The flour, meal, and other stored products containing these 

 larvae become foul and unfit for use. For remedial measures, 

 see flour moth and fumigation of mills, pages 345 and 353. 



The Saw-toothed Grain Beetle. This is one of our smallest 

 grain beetles (Silvanus surindmensis Linn.), being only one-tenth 

 of an inch in length. It is flattened in form and brown in color. 

 Six small points on each side of the thorax, like minute teeth, 



