470 ENTOMOLOGICAL NEWS. [Dec., '15 



Sceliphron caementarium. 



Nest taken. Date of emergence. No. of insects. 



August n, 1910. August 18, 1910 I 



August , 1910. September, 1910 2 



August 21, 191 1. June, 1912 3 



August 21, 1911. June, 1912 3 



August 21, 1911. June, 1912 i 



August 21, 1911. June, 1912 2 



August 21, 1911. June, 1912 9 



August 21, 1911. June, 1912 5 



August 21, 1911. June, 1912 i 



August 21, 1911. June, 1912 I 



August 21, 1911. June, 1912 2 



August 21, 1911. June, 1912 3 



August 20, 1909. June 22, 1910 2 



August 23, 1911. June, 1912 i 



August 21, 1911. June 20, 22, 1912 2 



August 21, 1911. June 22-28, 1912 3 



August 21, 1911. June 24, 1912 i 



September 10, 1911. June, 1912 5 



September 10,1911. June, 1912 3 



Chalybion cocrulcum. 



August 21, 1911. June, 1912 4 



August 21, 1911. June, 1912 I 



This is evidence sufficient to show that about August 21, or 

 a little before (since the above dates are when the nests were 

 taken and not when constructed), is the date when eggs then 

 deposited are destined to give adults in the spring. We are 

 sure that temperature is an important factor controlling the 

 time of hibernation, since cocoons removed from the nests in 

 January and kept in the living room gave forth their adults 

 in March. 



It would be interesting to find whether it is possible to get 

 the winter brood (that is the eggs deposited in August or Sep- 

 tember) to emerge in September or October by placing them 

 in an incubator. Those which normally emerge in August or 

 September must necessarily be destined to short lives and 

 probably have insufficient longevity to build and oviposit com- 

 pletely. 



A problem of equal inerest in this connection is whether 

 the insects of the first generation carry a greater number 

 of eggs than those of the last generation, in order that they 

 may utilize the summer to the benefit of the race. 



We have found that all of the wasps that hibernate in the 

 cells, emerge in May or June ; they begin nesting almost at once. 



