n] FOSSORES OR DIGGER-WASPS 7 



the human skin, nor do they ever make any attempt 

 to attack the observer, be he never so aggressive. 



Some of the most interesting and most easy of 

 observation among the digger-wasps are those known 

 to science as the Pompilids : we have about thirty 

 species belonging to this family, and fifteen of these 

 are included in the genus Pompihis itself. The in- 

 sects are rarely to be seen except in bright sunshine, 

 for they hide underground or crouch motionless and 

 difficult of detection when the sunshine passes away: 

 the mere shadow of a passing cloud is quite enough 

 to quench their activity for the time being. The 

 majority are black, or black and red in colour; a few 

 are black with creamy white spots. They all have 

 long, wiry legs, whose first joint (i.e. that nearest to 

 the body) or "coxa" is very large; the coxae of the 

 second pair of legs actually meet each other in the 

 mid-line underneath. The enlarged and closely ap- 

 proximated coxae are of great value to the insects 

 when excavating their burrows. These nest-tunnels 

 are often driven to a depth of several inches, and all 

 the soil to be removed is brought to the surface by 

 means of the enlarged and rather flattened coxae 

 which act like hoe-heads beneath the body and drag 

 the soil along the floor of the tunnel as the animal 

 backs up to daylight from the dark recesses of her 

 gallery: the close apposition of the middle pair of 

 coxae ensures that very little soil slips between to 



