262 KANSAS UNIVERSITY SCIENCE BULLETIN. 



excavated from her burrow. This wasp was less scrupulous 

 than the one just mentioned, for she stole soft earth freshly 

 excavated from its burrow from the tube of a neighbor — the 

 digger bee, Arithrophora occidentalis. These cases, of course, 

 are exceptional, for such poor economy is rare among the 

 Odij>ie7~i. 



When the nest has been provisioned its entrance is sealed 

 with mud. There seems to be no rule as to exactly where it 

 shall be. Of eight closed nests that I investigated in Rush 

 county, three were sealed in the basal end of the tube at the 

 entrance to the burrow ; two others were only at the distal end ; 

 the remaining three were in two places, both at the distal and 

 basal ends of the tube. Earth for closing the nest was gen- 

 erally taken from the cliff near the nest. 



In all their excavations and masonary these wasps use water. 

 Even when collecting earth from the sides of cliffs to close 

 their tubes they make frequent visits to streams. 



After the excavation of the nest it is provisioned with food 

 for the wasp grub. In all the nests that I opened a noctuid 

 caterpillar, apparently of the group Heliothinse, was used. 

 The largest of these caterpillars that I took from nests were 

 13 mm. in length. Some were as short as 10 mm. Their dorsal 

 color was dark red or reddish purple, with four longitudinal 

 white stripes. Ventrally they were greenish or purplish white. 

 I found this caterpillar feeding on the heads of several species 

 of sunflower {Heliantfms sp.), the gaillardia (Gaillardia 

 lutea) , and the purple cone-flower (Bramieria purpurea) . 



The number of caterpillars stored in each cell varied from 

 five to ten. The average per cell in Rush county was a little 

 more than seven caterpillars ; in Ness county the average was 

 nearly nine. According to these estimates, the average num- 

 ber of caterpillars that should have been stored in an average- 

 sized Rush county nest is thirty. The average number of 

 caterpillars in an average Ness county nest should have been 

 fifty-four. The largest nest that I found — one with fourteen 

 cells — should, according to the Ness county average, have con- 

 tained 126 caterpillars. 



The largest number of caterpillars that I actually found in 

 a single nest was fifty. This nest had eight cells. In two of 

 these cells there were no caterpillars, for the wasp grubs 

 within were full grown. In another cell there were seven 

 caterpillars and a small wasp grub. In the other cells the 



