THE GRAPE-LEAF SKELETONIZER. 85 
SEASONAL HISTORY. 
NUMBER OF GENERATIONS. 
Former writers have generally attributed two generations and 
a partial third to this insect; in fact, all, with the exception of Neal. 
who states that there are three broods in Florida, are of the opinion 
that there are two broods. Extended observations and studies dur- 
ing the past summer reveal the fact that there are not two full gen- 
erations in the vicinity of Washington, D. C. Seasonal history 
studies show that moths from the over-wintering pup appear dur- 
ing the latter part of May or chiefly during the first ten days of June. 
Eggs from these moths were found June 11, 1908, and also a few very 
young larve. By June 30 some larve were almost fully grown, but 
the majority of full-grown larve did not appear until about July 14, 
although a number of pupez from the early-developing larve were 
found on July 7, showing a long period from the appearance of the 
first full-grown larve to the appearance of those which attained their 
growth at the latest date. 
The second generation of moths, or those from first-generation 
larvee, appeared continuously from July 18 to August 15, giving a 
very extended period of emergence and accounting for the tendency of 
former writers to attribute the late-appearing ones to a third genera- 
tion. 
The largest number of moths appeared from July 20 to 25. A 
number of those larve which had attained their growth by July 14 
hibernated as pupe and did not emerge as moths, thus showing clearly 
that there was not a full second generation. 
Eggs from the second-generation moths were most numerous from 
July 20 to 23, with many second-generation larve appearing on July 
27. Some of the second-generation larve were full-grown on August 
24 and were spinning cocoons on that date and up to September 16, 
when all had gone into cocoons. 
LIFE CYCLE. 
The average length of the life cycle was found by adding together 
the average lengths of egg stage, larval period, time spent in cocoon, 
and life of moth. The average length of the egg stage was 7.92 days, 
the average length of the larval period 40.5 days, the average time 
spent in cocoon 14.8 days, and the average length of life of a moth 
3.5 days; thus, the average length of the complete life cycle was found 
to be 66.72 days. The minimum life cycle, found by taking the mini- 
mums of the various periods and adding them together, was 53 days. 
All of these averages were taken from a very large series under 
observation. While the above figures should not be taken and used 
to find how many generations there are in any given locality, they 
will give some clue to the time required for the development of a 
