iQoS] Gregariiis Sleeping Habits among Hymenoptera i29> 



No less than seven species of aculeate Hymenoptera were 

 represented in large numbers, belonging to three different families, 

 four sub-families and fi\'e genera, and each species so far as 

 observed was always grouped separately. Though a group' 

 of one species were in close juxtaposition to that of another on a 

 neighboring stem there was no intermingling of individuals. 



Returning on a subsequent evening a week later (but perhaps 

 not finding precisely the same place at a favorable time) , I found 

 the bunches of wasps less abundant, but still present, and found 

 a few groups of an eighth species. 



The species found on the first night were Chlorion (Priononyx) 

 atratum; C. (Priononyx) bivefoleatum ; two species of Sphex 

 (formerly Ammophila-synonym of Sphex) ; Monedula emarginata ; 

 Steniola duplicata, and Stizus unicinctus, the last two being 

 especially common. On the second visit the above were found, 

 and one additional species, Sphecius fervidus Cr. On both occa- 

 sions, there were a few individuals of one or two other species, 

 notably bees, Bombus, sp., Halictus farinosus and Melissodes 

 agilis, etc. 



I am indebted to Prof. Fernald for the identification of the 

 SphegidcE and to Mr. H. L. Viereck for that of the others, except- 

 ing Sphecius fervidus, which is my own determination. 



The vegetation in that part of the San Joaquin Valley had 

 already for over a month been scorched dry and brown by the in- 

 tense sun-heat and absence of rain. Along one side of the road 

 in the canon the vegetation had been freshly burned off by ex- 

 tensive prairie fires. Along the other side was a field of recently 

 cut grain with a narrow standing strip along the road in which 

 were situated the groups of wasps, not only on the oats, but on 

 one or two other dried plants. We found them at intervals for 

 perhaps a mile or more and then it became too dark to see further. 

 Not everywhere along the road were the conditions as above des- 

 cribed, in some cases the bunches occuring in a tangled growth 

 of dried weeds. 



On subsequent evenings I hunted in vain for sleeping wasps in 

 the sage brush and fox-tail grass on the plains, twelve miles dis- 

 tant. No trace of the wasps was to be found. 



The fact that the "hostelry" described by Mr. Banks was also^ 

 bordered by a field of recently cut grain may not be a mere coin- 

 cidence. It is quite possible that normally these wasps are scat- 

 tered through such fields when sleeping at night, and that by the 



