396 Annals Entomological Society of America [Vol. XI, 



2 to 3 mm. in length. The disparity in size is accourited for by 

 earlier or later hatching the previous summer, and because of 

 this fact, and since no individual life history could be traced, 

 no significant comparisons as to size between these larvae, or 

 with that of the preceding autumn, can be made. 



It can be stated that the larvae have a comparatively slow 

 growth, a large number of ecdyses, that they overwinter at the 

 bottom of the water, and must pass through considerable of 

 their growth in late spring. 



Old larvae were obtained (in 1917) from June 17, when this 

 work was begun, to July 22. The distribution over this period 

 and relative abundance of maximum size old larvae shows that 

 in this locality the mean date for their full growth is during the 

 first week in July. 



Pupa. 



The pupa is short-lived. It was not found in nature, but 

 many old larvae pupated in the laboratory, and, although there 

 was a rather high death rate, due to molds, a number completed 

 their life history. Out of 25 pupae, the time of pupation of 4 

 was not secured, and 12 died before emerging as imagoes. The 

 records of the other 9 show an average pupal period of about 



3 days. 



Adult. 



The beetle was first caught on Jul}^ 4, but only three were 

 then secured. This date corresponds pretty well with that of 

 the first emergence of the beetle, in the laboratory, July 6. In 

 nature the beetles became increasingly more abundant up to 

 the latter part of the month, after which there was a rapid 

 decline until the last week in August when no more were 

 captured. 



The life stages obviously overlap during early and middle 

 summer, when at some favorable time old larvae, pupae, adults, 

 eggs, and even young, new larvae may exist simultaneously. 

 The period for each life stage is pretty well marked off though 

 with a maximum point of abundance for each. 



A summary of the life history (which seems reasonable even 

 from the incomplete results) shows an egg period of about ten 

 days, a larval life of about eleven months, a pupal period of 

 three days, and an imaginal existence of possibly a week or two, 



I 



