494 THE SMALL GRAINS 



The dark meal-worm (Tenebrio obscurus, Linn.) has the 

 same habits and life history as those of the yellow meal- 

 worm, and is found in the same places. The adult beetle 

 is similar in size and shape, but is dull pitch black in color. 

 The larva also resembles that of the yellow meal-worm in 

 size and shape, but differs in color, having much darker 

 brownish markings. 



538. The confused flour beetle (Tribolium confusum, 

 Duv.). This insect is native in the Eastern Hemisphere, 

 but since 1893 has become a serious pest in the United 

 States and southern Canada. While primarily a flour 

 pest, it also infests corn meal, cracked wheat, and many 

 other dry foods. Of mill products, it prefers the low- 

 grade flours, but is often found in large numbers in the 

 best patents. 



The eggs are very small, clear white in color, and are laid in cracks 

 and corners of bins, and in seams and creases of sacks, and in cracks 

 and on the sides of boxes, barrels, or anything containing cereal 

 products. These hatch in summer in about 5 days, producing 

 small white worms inch long, which, after about 24 days of 

 feeding, change to naked white pupse. The pupae remain so only 

 5 or 6 days, when the adult insects emerge, making the total life 

 cycle about 5 weeks, with a temperature above 85. At lower 

 temperatures the life cycle is from 14 to 15 weeks. The beetles 

 are ^ inch long, flattened, rust-red in colon, and very common in 

 flour. With favorable temperatures there are at least 5 broods 

 annually. 



This insect is found in mills in all stages, and is espe- 

 cially abundant in accumulations of flour in elevator boots 

 and flour conveyors. It breeds in cracks in the floor and 

 in mill machinery (Dean, 1913, pp. 210-212). 



539. Other flour beetles. There are 4 other flour 

 beetles of less importance than the preceding. The rust- 



