1408 



ZOOLOGICAL SOCIETY BULLETIN 



f.„ 



FURROWS MADE BY THE ANT-LION 

 This is done to tempt insects to follow the path to the crater. 



eral ants, among the multitude treading tlie 

 masses between the slain, were observed to top- 

 ple into the funnel, and one ant slid to destruc- 

 tion as it dragged away the shriveled body of 

 another. 



Not all of the funnels fared as well, for some 

 portions of the colony appeared to have few 

 insect visitors and changes of funnel locations 

 to better food areas were indicated by deserted 

 craters into which had blown tiny wisps of 

 debris. This is a positive indication of an un- 

 used funnel, as the ant-lion keeps the bottom of 

 its crater scrupulously clean. If there is a gen- 

 eral scarcity of insect wanderers over the area 

 occupied by the colony, the ingenious trappers 

 resort to tactics calculated to lead every stray 

 creature directly to their pit-falls. They issue 

 from the craters and by wriggling backwards 

 over the level ground plow mazes of undulating 

 trails. The tendency of small, roaming insects 

 is to follow a furrow, and the trails lead always 

 to the sandy trap with the omnipresent jaws 

 and sand-laden heads of the watchful ant-lion. 



The writer experimented with a colony far- 

 ing poorly and already marked with several en- 

 ticing trails, by building a miniature parapet of 

 tin, about three inches high, around the entire 

 area, debarring ground-strolling insects. After 

 two days the ant-lions adopted the most vigor- 

 ous measures, marking out the enclosed area 

 with an elaborate system of furrows that curved 

 and twisted in every direction. 



Upon leaving the South, about thirty of the 

 ant-lion larvae were dug from the bottom of 

 their pit-falls, placed in flat tin boxes contain- 

 ing their native sand, and with a box of the 

 sand were shipped north in order to restart a 

 miniature colony. The little creatures neces- 

 sarily were without food for eight davs' time. 



but all survived the trip. A tra}^ eight feet long 

 by four feet wide was filled to a depth of about 

 three inches with the transferred sand, and 

 within an hour after the ant-lions were placed 

 in the trav it was populous with their craters. 

 It was from this batch of larvae that the photo- 

 graphing of the life history was completed. 



The collected larvae were from eggs laid in 

 the late fall of 1915, which had remained un- 

 hatched through the mild southern winter until 

 early spring. The larvae were full grown when 

 collected on the 5th of INIay, and the colony in 

 the tray was established on the 14th of May. 

 The craters remained in active operation until 

 the 20th of June, when debris accumulating in 

 one after another indicated a transition into the 

 pupal form, which inactive state precedes the 

 emergence of the perfect insect. 



When all of the funnels had become inactive, 

 the sand was screened and from it the cocoons 

 were collected. They were perfectly spherical 

 and appear like a ball of sand that has adhered 

 as a moist spot cakes and hardens. 



They are about half an inch in diameter, but 

 when rolled between the fingers they continue 

 to shed sand particles until they are reduced 

 fully a third in size. They are then seen to be 

 tightlv spun cocoons of silkj^ substance. When 

 opened, shed skin of the larva and the pupa are 

 found. It wriggles vigorously and completes its 

 development as well as if encased, showing the 

 translucent wing cases, large green eyes and a 

 head much like that of a dragon-fly. After be- 

 ing examined and photographed the cocoons 

 were again buried in the sand and the first of 

 the perfect insects emerged thirty days later. 



The final stage of the ant-lion is a delicate, 

 gauzy-winged creature somewhat like a dragon- 

 fly in form, but with a fluttering, slow flight. Its 



^ 



AN ANI-LION Al IIOMI''. 

 Only the threatening mandibles are exposed. 



