186 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



Little is known concerning the amount of injury done by the adults. 

 Swenk (1909, p. 336) states that the beetles fed voraciously on corn 

 leaves in the breeding cages. When the experimental work was started, 

 the adults were supplied with various weeds found in the wheat field, 

 but in no case did they feed to any extent and the mortality was high. 

 A few of the beetles fed sparingly on smart weed, dried wheat leaves, 

 and fresh wheat leaves. Wheat heads that were not yet mature were 

 then introduced into the cages and the beetles began to feed on them 

 at once. Later soaked wheat kernels and bran were supplied and they 

 fed on these readily. Mating and oviposition began soon after the 

 change to this food. The fact that the beetles fed on the wheat heads 

 and grain suggests the possibility that they may feed on them in the 

 field, and in fact, recent investigations bear this out since typical injury 

 has been found on wheat in the shock. It is not unusual to find large 

 numbers of beetles about the shocks and stacks of wheat, and in many 

 cases the fall infestation has radiated from such places. 



Description and Life Economy 



Method of Rearing. — The same methods were followed in the 

 rearing of Eleodes opaca as were described by the writer (1918, pp. 214- 

 215) for the life-history work with E. tricostata. The eggs were kept in 

 the field insectary while the other stages were kept in a cement cave. 



Egg. — The eggs of Eleodes opaca (Plate 8, A) closely resemble those 

 described for other members of the genus, being oval in shape longitu- 

 dinally, and circular in diameter. They show some variation in size, 

 being from 1.1 to 1.4 mm. in length and from 0.50 to 0.65 mm. in width. 

 They are white in color when deposited and change to a creamy yellow 

 before hatching. A sticky secretion covers the egg, causing particles of 

 soil to adhere to it. In the breeding cages the eggs were deposited in 

 cavities in the soil ranging from one inch to five inches in depth. 



The length of the egg stage varies with the temperature, and the 

 season of the year. Eggs deposited during midsummer hatched in 

 from 6 to 10 days, while later in the fall the stage was prolonged to 19 

 days. The first oviposition recorded occurred on July 5, and the last 

 on October 4. The exact length of the egg stage was determined for 

 993 eggs, as shown in the following table: 



Average 9 . 7 



