INSECTS 



189 



top (fig. 144), so that the site of the tunnel shall be as 

 nearly indistinguishable as possible. 



Ammophilas are common all over the country, and the 

 nest-building of various species has been watched by other 

 observers. The use by an indi- 

 vidual Ammophila of a small 

 pebble, held in the jaws, as a 

 tool to pound down and smooth 

 off the earth has been twice 

 recorded, once in Wisconsin and 

 once in Kansas. These are per- 

 haps our only records of the use 

 of a tool by an insect. 



Very interesting accounts of 

 the habits of various digger-wasps may be found in "The 

 Solitary Wasps," by George W. and Elizabeth G. Peck- 

 ham ; also in ' ' Insect Life ' ' by Fabre. 



The best general reference-book for American students 

 of insects is Comstock's " Manual for the Study of In- 

 sects." " Insect Life," by the same author, gives prac- 

 tical directions for much interesting observational work 

 on habits and external structures. Howard's " Insect 

 Book " is recent and interestingly written. 



Fig. 147. — The plum curculio, 

 Conoiracheliis 7ieiiuphar^ a 

 beetle very injurious to plums. 

 (Pliotograph \>y IVI. V. Slinger- 

 land.) ' 



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