INSECTS INJURIOUS TO CEREALS 245 



to it they will eat almost anything. We have had a colony 

 of them living on corn in the ear in the insectary for several 

 years. The larvae seem to thrive upon the corn and go 

 on reproducing the whole year through. 



Life history. The egg is elongated, oval in shape, and 

 when first laid almost white, but later it turns brown and 

 becomes wrinkled. The egg is visible to the unaided eye, 

 but so small that it takes forty to fifty of them, placed 

 end to end, to reach an inch. In our cages the eggs 

 were deposited on paper and cloth and on the sides of 

 the glass tumblers in which the moths were confined. 

 It takes the eggs from five to ten days to hatch after being 

 deposited. 



When the caterpillar first emerges from the egg it is 

 only about one-twenty-fifth of an inch long. But it 

 eats a great deal and grows rapidly, so that in midsummer 

 it becomes full-grown in 25 to 40 days. In early spring 

 and late fall, when the temperature is lower, it takes longer 

 for the larva to mature. When the larva is full-grown, 

 it spins a very fine thin cocoon of silk and within this 

 changes to a pupa. The cocoon is usually fastened to 

 some surface, and often particles of flour and meal are 

 mixed with the silk. The pupa rests quietly for ten or 

 fifteen days and then its skin splits open along the back 

 and the moth crawls out, dries its wings, and perhaps flies 

 to other parts of the house. The female moth is soon 

 ready to deposit her eggs, which in our cages were laid 

 mostly at night. Sometimes the eggs are laid singly and 

 sometimes in chains of eight or ten. Johnson has shown 

 that a single moth may lay as high as 271 eggs with an 

 average of about 240. 



Under natural conditions in the East there are probably 



