THE CANADIAN ENTOMOLOGIST. 11 



across from the entrance, and about the same in depth, with a downward 

 slant towards the burrow. Larvce dug out and watched, dug new holes in 

 the following manner : The burrow was begun much on the slant, and dug 

 back for some two inches, gradually turning downwards until a 

 perpendicular position was arrived at. In excavating the pit the larva 

 reached out and threw the earth backward, and in doing so gradually 

 worked the burrow back until it became about a quarter of an inch from 

 the surface. This made approximately the correct length of the pit. The 

 Inrva now turned its attention to deepening the pit. This was accom- 

 plished in the individual watched by constructing an auxiliary hole from 

 the perpendicular one horizontally into the bottom of the pit. The earth 

 was then worked up from below, and shoved round the chief entrance 

 until it became blocked, when the insect returned and threw the earth 

 backwards from the main burrow. This operation was repeated a number 

 of times, until the pit became nearly full depth, but its completion was not 

 observed owing to the larvae devoting its energies to the chief burrow for 

 several days. The pits usually become partly or wholly filled up when 

 the larvse deepen their burrows before hibernating, and therefore have to 

 be cleaned out again in the spring, but whether this is done by means of 

 an auxiliary hole or not is doubtful. Some burrows examined showed 

 signs that such was the case, others left no indication. The larvae are 

 very active, both in and out of their holes. 



There is no doubt that the pits act chiefly as traps for insects such 

 as ants, which are captured while endeavouring to make their way out. 

 Experiments of throwing small ants in resulted in their immediate capture 

 as soon as they reached the bottom, with such rapidity that it was difficult 

 to see how they were seized, though the larva had to reach out fully half 

 its length to secure them. Small bugs, when touched, which was seldom, 

 were at once rejected. 



The pits also act as a protection against drifting sand and heavy 

 rains, but this is probably accidental, as the burrows are seldom in very 

 open places, and are often where the sand never drifts. 



Twenty larval holes of the second year were measured when the 

 insects had finished digging. These showed an average depth of 66 

 inches, the shallowest being 50 inches, and the deepest 79 inches. Four 

 others were over 70 inches below the surface. 



The larval stage of Manitoba lasts opproximately 24 months, and the 

 adult about 12. The pupa has not been observed. 



