Eleventh Report of the State Entomologist 235 



greatest peculiarity is its utter incapability of making the least progress 

 in a forward direction, its legs being so constructed that it can only move 

 backward. How then can the creature, it may be asked, provide itself 

 with its needed supply of food ? It can only do so by a resort to a cun- 

 ning artifice. 



Its Pitfall. 



It constructs a pitfall in which to entrap its victims. Its home is be- 

 neath some overhanging ledge of rocks, the disintegration of which 

 furnishes the material and the shelter needed, such as are offered by the 

 Pentamerus rocks of the Helderberg formation. Depressing the end of 

 its abdomen, it buries its body beneath the sand-like particles of the 

 rocks, and moving around in a circle and throwing outward, with quick 

 and frequent jerks, the sand which falls on -^, ..^.g^iasaiSi^ 

 its fiat head, it marks in a deep furrow the cir- |?^°^^i^^^|^&^ii,'' 

 cumference of its pitfall. Within this a slightly M^WS^t^^^^^^^^^M^ 

 smaller and deeper circuit is taken, and succes- ^^'^^0<^iPW^^^^^^^^ 

 sive smaller and deeper ones, all the materials „ r.- /„ V a ,• ,^^ 



^ ' Fig. i8.— Pitfall of Ant-lion. (Af- 



from within being meanwhile loaded upon its ter Emmons.) 



head, and by it thrown upward and outward, to the distance sometimes 

 of several inches. By this means, by dint of much hard labor, especi- 

 ally when a piece of stone requires to be nicely balanced upon its head 

 for its proper projection, a symmetrical funnel-shaped pit is at length con- 

 structed, the walls of which are as steep as the mobility of the material 

 will permit. (See Fig. i8.) 



The pitfalls vary in size according to the age of the insect, some being 

 but about half an inch in depth, and the largest perhaps two inches. 



How the Prey is Captured. 

 The pit having been completed, the ant-lion buries itself at the bottom, 

 with only its mandibles exposed, and widely spread apart, ready to grasp 

 its prey. An ant traveling over the surface of the soil, unsuspicious of 

 the trap, would perhaps endeavor to arrest its steps on the very margin, 

 but the crumbUng sand at once gives way beneath its struggles, and down 

 it falls into the very jaws of death. If by chance a foothold is obtained 

 on the sloping side, the watching ant-lion at once projects showers of 

 sand which never fail to bring its victim down. It is instantly seized by its 

 long curved mandibles and dragged beneath the sand to prevent its strug- 

 gles. The mandibles of the larva are peculiarly adapted to the needs of 

 the insect. On the lower side of each, a groove extends to the tip and in 

 this the elongated maxilla is located (Fig. ijc). The sharp pointed 



