3 2 IV. Dwight Pierce 



with other Fossores. Cercens sp. might easily have stored in 

 Eptnomta nests. I have found Osmia nesting in holes and cells 

 of Melissodes obtiqua the year following their digging by obhqua, 

 and the second year the same cells were occupied for the summer 

 by Fossores and by spiders. The third year obliqua was again 

 nesting along the same bluff." 



The author has not yet noticed this alternation by dwellers in 

 the communities under observation. Since 1900 Mr. Crawford 

 and the author have watched these holes carefully and Efinomia 

 has been almost the sole occupant. As for Cercens it has not 

 vet been taken in the vicinity of the holes, nor has any other 

 wasp besides Ammophila outside of the three families Pemphre- 

 donidae, Mimesidae, and Crabronidae. 



MEMBERS OF THE EPINOMIA COMMUNITIES 



Epinomia triangulifera Vachal. 



This bee lives on Helianthus aiiniius and its season coincides 

 with that of its food plant. The bees come out late in July or 

 early in August, and by September 19 are all gone. Some "time 

 later than that the author visited the holes and found that by 

 scraping away not more than half an inch of the surface the 

 holes were laid bare. This was in early October and the only 

 forms in the holes were the larvae. On August 20, 1903, in 

 digging out holes, the author found the bee in the larval, pupal, 

 and imaginal stages in the holes— in fact there were all grada- 

 tions from larva to imago. The holes are 7 to 9 mm. in diameter 

 and go straight down about twenty-one inches. Three or four 

 galleries about three-quarters of an inch in length extend out- 

 ward, horizontally, near the bottom of the hole. 



Myodites solidaginis Pierce. 



This beetle is the most prominent parasite. Its habits are 

 recorded on the preceding pages. Females have never been 

 found at the holes. Males have been caught hovering over the 

 holes on August 23, 1903, and August 25, 1901. On the former 

 date a male was also found in a hole and also the pvgidium of 

 another, and from the contents of the cells fifteen triunguloids 

 were collected. 



184 



