214 THE HARMONIES OF NATURE. 



intended victims, buries himself entirely in the sand, with the 

 exception of the points of his expanded mandibles. It is not 

 long before some curious ant or inquisitive little beetle approaches 

 the yawning abyss ; but no sooner does it step upon the margin 

 of the pit, than the treacherous sand gives way under its feet; 

 its desperate struggles only hasten its descent, and, rolling down 

 the yielding sides of the pit, it is precipitated headlong into the 

 jaws of its concealed devourer. 



Sometimes, when a more powerful insect chances to fall into 

 the pit, the ant-lion does not obtain a meal on such easy terms, 

 and a regular battle ensues; the victim, in its furious endeavours 

 to escape, bringing down the sand in torrents, which the ant- 

 lion, to avoid being overwhelmed, flings up again as fast as he 

 can. During this conflict a fortunate shower of sand striking 

 the intended prey may knock it over, and bring it within reach 

 of the devourer's terrible jaw, or it may give over through sheer 

 fatigue ; but sometimes, the pit gradually filling up, and render- 

 ing the slope of the sides shallower, it succeeds in making its 

 escape from the den, leaving the baffled 'ogre' to mourn 

 over the desolation of his shapeless and ruined dwelling. 



Though it does not dig an artificial pitfall, the larva of the 

 tiger-beetle catches its prey in a somewhat similar manner. It 

 lives in perpendicular burrows, about a foot in depth, which it is 

 able to traverse with great rapidity, and which are only just of 

 sufficient diameter to permit the inhabitant to pass up-and-down ; 

 ascending to the upper portion of its burrow by means of the pair 

 of bent hooks that rise from a humplike projection on the lower 

 part of its back, and then laying its jaws level with the soil. While 

 in this attitude it is almost invisible, and as soon as an insect 

 passes by the ambushed larva the sickle-like jaws grasp it, and 

 it is dragged to the bottom of the tunnel, where it is devoured. 

 Not only is the larva carnivorous, but it is combative in pro- 

 portion to its voracity; so that if a straw be thrust into its bur- 

 row, it will fasten upon it with the obstinate fury of a bulldog, and 

 suffer itself to be dragged out of its home rather than let go its 

 supposed enemy. The burrow, which is the larva's own work, 

 costs it both time and trouble; the earth being loosened by means 

 of the feet and jaws, and then carried to the surface or the flat- 

 tened head. 



Of the insects it may truly be said that the part they play in 



