374 W. D. FuNKHOUsER 



DURATION OF EGG STAGE 



Since most of the species winter over in the egg stage, the period of 

 incubation for these eggs cannot be exactly determined. For those species 

 that show several broods a year, however, it is possible to determine the 

 duration of the egg stage. This has been noted both in the field and in 

 the laboratory. The average length of this period is approximately twenty 

 days. Miss Branch (1913:84) has found that nine daj^s represents the 

 egg stage of Entylia sinuata. No local species has shown so short a 

 period. Wildermuth (1915:349) reports cases in which only twelve days 

 are required for incubation of Stidocephala festina, but gives the average 

 as twenty-two days, with a maximum of forty-one days, depending on 

 the prevailing temperature. Even more remarkable is the record of 

 Mr. Gibson, in Greenwood, Mississippi, who noted an incubation of 

 the same species in four days (Wildermuth, 1915:349-350). In the 

 course of this study no experiments with artificial temperatures in respect 

 to temperature variation in the length of the egg stage have been made, 

 but, as will be noted under the subject of ecology, the natural climatic 

 conditions have had a decided influence on the incubation of the egg and 

 the development of the nymphs. 



DATES OF HATCHING 



The time of hatching of the eggs depends largely on climatic conditions, 

 being much later in some years than in others, but considerable variation 

 is found in eggs of the same species in the same season. A difference of 

 two weeks between the appearance of the first and the last records in 

 the field is not unusual. It is presumed that in such cases the eggs hatching 

 first were those deposited earliest in the preceding fall, but this is not 

 known to be true. 



Even in the same egg mass the eggs do not all hatch at the same time, 

 a difference of nearly a week between the first and the last having been 

 observed in some cases. The explanation of this variance is not forth- 

 coming, since of course the eggs may be assumed to have been laid at one 

 oviposition and the environmental conditions were identical for all. 



MECHANICS OF HATCHING 



The mechanics of the process of hatching is practically the same for all 

 species studied. A few days before hatching, the egg appears somewhat 



