Beyer: Trogoderma inclusa. 375 



EXTENT OF INFESTATION. 



x\s stated before, fifty per cent of tlie colhirs in one factory were 

 damaged. I made a careful dissection of both sides of a badly 

 infested collar by removing the leather of the facing of the collar. 

 I have found only llie larval stage of the life cycle in the collars 

 so far examined. T made an approximate count of all the larvae 

 found in this collar, and 900 larvae was the result. I also counted 

 the number of holes in the same collar leather, to get the per cent 

 of damage done by each insect. The actual number of holes in this 

 collar made by. this pest was 424. Approximately 1,324 of the in- 

 sects infested this collar. 



The larvae varied from 2i/^ to 5 mm. in length. They were 

 usually found in the heads of the rye, or eating on the scattered 

 grains. The larvae eat straight across the ends or sides of the grain, 

 something as a mouse gnaws, and not after the fashion of the grain 

 borers. Wherever the tunneling or eating process was found, I also 

 found evidence of molting. I found small larvae emerged in heads 

 of rye, which is e\'idtnce that the eggs had been laid in the heads. 



LIFE HISTORY OF THE BEETLE. 



In making dissections of the collars which had been incubated 

 at a constant temperature of 70 degrees for several weeks, I found 

 various sizes of larvae and a number in the pupal state. None 

 was found in the adult state. No eggs were found in the collar dis- 

 sections. 



MATING AND OVIPOSITION. 



The beetles I found in all cases mated a day or two after emerging 

 from the pupal skins. The eggs varied in number from ten to fifty. 

 They were placed around indiscriminately on the bottoms of Petri 

 dishes from four to six days after copulation. In a number of cases 

 the female oviposited on the rye placed in the dishes, and the eggs 

 adhered to the rye by means of little filaments projecting from one 

 end of the egg. The young larvae hatched from eight to twelve 

 days later at ordinary room temperature. The young larvae, soon 

 after hatching, began to feed on the material at hand. They did 

 not wander unless food was scarce or poor. I reared them entirely 

 upon rye grain. The growth of the larvae depends to a considerable 

 extent upon temperature and the abundance of food, and it is re- 

 tarded by weather and scarcity of nourishment. The foregoing 

 factors are not, however, the only causes of slow development. 

 I noted in my experiments that the growth of specimens varies 



