isely: eumenid^ of kansas. 243 



grass. The cells are broadly spindle shaped, pointed at one 

 end, which is left open until the cell is stored. The chambers 

 do not touch each other for more of their length than is neces- 

 sary for their mutual agglutination. This almost entire inde- 

 pendence of the cells entails a considerable waste of building 

 material as compared with the habit of Peloj^seus cenentarivf>. 

 which builds its cells side by side in rows and tiers of rows." 



A day's work with O. dorsaUs is to provision one cell and 

 construct another. The newly constructed cell is used as a 

 resting place for the wasp herself during the first night. 



In order to take a picture of the nest, Mr. Hartman pulled 

 away some grass blades and set up his camera. This disturbed 

 the wasp very little. "After once flying away for a minute," 

 he writes, "and circling about once or twice, she settled and 

 placed the caterpillar in the nest. . . . This done, she 

 cleaned her antennae and flew away without seeming to take 

 her bearings." 



Very small caterpillars — cotton worms — were stored. Of 

 seven found in one cell four responded perceptibly to stimula- 

 tion. The author believes that Odynerus occasionally takes a 

 caterpillar for her own delectation. He also observed this wasp 

 picking up unwary ants that passed too near her as she was 

 lying in her cell one morning before going to work. 



From six cells four wasps emerged in thirty-nine days each. 

 The length of the stage for the egg and larva together was 

 twenty days. The other two wasp larvae were killed by mites. 



I shall quote nearly the whole of Mr. Hartman's notes on 

 0. arvensis. He writes : 



This species of Odynerus does not possess the architectural skill of its 

 cousin just described. Its home is not such an elaborate domicile, built, 

 as it were, for show as well as for use, but consists of any convenient 

 crevice in a wall or fence post. The nest is completed by closing the open- 

 ing of the crevice with mud, much after the fashion of Trypoxylon. I have 

 made a few observations on two nests of this Odynerus; those on the con- 

 ditions of the caterpillars found are of particular interest. In general 

 the following facts do not justify Fabre's conclusion, which he based on 

 the habits of O. rcniformis. 



At noon August 4 a female ai-vensis was closing her nest in the niche 

 of a brick wall. A few days before a Trypoxylon had emerged from the 

 very niche now intended to be the cradle of another wasplet. I immedi- 

 ately opened the nest and drew out eight caterpillars, all of which were 

 alive— six of them, in fact — so lively that they wriggled around in the 

 small vial to which I had transferred them. I found no egg at first, but 

 looking carefully into the dark recess, I discovered the egg suspended 



