RESULTS OF CROSSING. 325 



The last pair of bugs of the original three pairs never mated, 

 although they were kept under observation until October II. 

 They were then added to a cage containing eight specimens of 

 the same cross (49 and 40") which we had caged to carry 

 through the winter. 



The record of the first pair shows that from August 15 to 

 August 25, 34 eggs were deposited and that only one of these 

 developed. If we add to these the above-mentioned 26 eggs 

 from the second pair of this cross, we find that out of 60 vario- 

 larius eggs, that were presumably fertilized by ictericus, only 

 one developed and hatched. 



Comparing these results with those of the cross between 

 variolarius X servus, we find that in the latter a very much 

 larger proportion of eggs developed, for out of a total of 120 eggs, 

 37 developed and 32 of these hatched. 



This contrast between the results of the two crosses is greatly 

 increased if we add the number of eggs deposited by the vario- 

 larius-ictericus .cross of the summer of 1912. As stated above 

 we caged through the winter of 1911-12 five female variolarius 

 and five male ictericus. All of these were reared in the laboratory 

 from the same stock as those of the 1911 pairs. Only one of 

 these mated the next season (cage 12, 1912). Of the 53 eggs 

 which were deposited between June n and July 15 not one 

 developed. We believe we might have had better success with 

 wild males; but we failed in our efforts to get them in the spring 

 of 1912. In summing the results we find that 113 eggs in all 

 were deposited by the three variolarius females that were crossed 

 with ictericus and that only one of these 113 eggs hatched; 

 the remaining 112 did not show even the initial stages of de- 

 velopment. This one egg that developed was deposited August 

 1 8 and was not hatched until August 28, as the weather was 

 unseasonably cold. The nymph (a female) reached the winged 

 stage September 26. We succeeded in keeping this hybrid in 

 good condition through the winter of 1911-12, and the following 

 June she mated with a pure ictericus. The record of this pair 

 is as follows: 



