Beyer: Trogoderma inclusa. 381 



adaptation to food supply. 



An interesting phase of the study of the life history was the ex- 

 tremely long period of time the larvae can sustain themselves with- 

 out food. I placed forty larvae in Petri dishes^ ten representative 

 stages, varying from newly hatched to full-grown individuals, with- 

 out any food whatsoever, for the purpose of determining the period 

 required to produce starvation. I also added a number of Petri 

 dishes, each containing one larva ranging from 1 to 6 mm. in length, 

 and another Petri dish was added, containing a number of a definite 

 size, to determine whether they would eat their skins or not. Meas- 

 urements were made of all the individuals and records kept. Dishes 

 were examined regularly and measurements made of the representa- 

 tive stages. I also made a record of the cast skins. I found that 

 the larvae never devour the molted skins of themselves or other speci- 

 mens. I detected no evidence of cannibalism among the larvaB, even 

 the full-grown starving specimens never attacking the much smaller 

 individuals. Practically all of the larvae shed their skins shortly 

 after being deprived of food, but the molting process from this on 

 was very much slower. The measurements showed in all cases that 

 the different larvae decreased in size about one-half their normal 

 length after eight months of life at a temperature of 70 degrees and 

 in ordinary daylight. The newly hatched began to die when about 

 three months old. The larvae of the middle stage up to the adult 

 stage were all still surviving, and judging from existing circum- 

 stances, the survival, especially of the full-grown larvae, would be 

 considerably over one year. Experiments were carried on with 

 reference to different kinds of diets or foods taken from the collar, 

 as rye seed, rye straw and leather, and in drawing comparisons it was 

 found that they thrived and grew rapidly upon the rye seed, but 

 refused any of the other materials contained in the make-up of the 

 collar. 



CONTROL MEASURES. 

 HEAT. 



I first took the trouble to look over the field of available literature 

 relative to the control of this class of insects. I found that the 

 French were the first to know the value of heat, and to devise con- 

 trivances for the heating of infested buildings. Experiments were 

 made by Professor Webster to ascertain the amount of heat required 

 to destroy the Angoumois grain moth, which gave the following 

 results : 



