256 BEVERLY WAUGH KUNKEL 



Lucilia, as a rule, lays its eggs on meat before decay has set in, 

 within a few minutes after the animal has been killed, while 

 Sarcophaga is attracted to meat which has advanced somewhat 

 in the process of decay. Most of the observations made in this 

 investigation were on Lucilia which is the most abundant genus 

 of flesh flies in this region during the period of these observations. 

 The eggs of Lucilia are laid in masses of about one hundred. In 

 a large number of observations I found that the flies prefer 

 crevices or cavities in which to deposit their eggs, at least these 

 situations are the first to receive eggs, later the more exposed 

 portions become 'blown' as welL- 



As flies of different species sometimes lay their eggs in close 

 contact with each other so that the limits of the two or more masses 

 cannot be distinguished, care was taken to use only isolated egg 

 masses of comparatively small size which were laid soon after the 

 meat was exposed to the flies. 



The eggs of Lucilia hatch in about twenty-four hours and the 

 larvae at once begin to liquefy the food material. They work 

 beneath the surface, excavating cavities into which they sink. 

 Finally the whole mass of food may be reduced to'' a thick, gray 

 broth through which the larvae move freely. The larvae are very 

 strongly negatively phototactic and are apparently very sensitive 

 to variations in temperature and in the composition of the 

 atmosphere. If for any reason, such as improper ventilation, the 

 conditions in the culture glass in which the larvae are feeding 

 become unfavorable, within less than a minute there is a whole- 

 sale movement on their part to escape. 



L. caesar and sericata are very closely related species which 

 are distinguished by the arrangement of the spines on the thorax. 

 I am indebted to Mr. V. A. E. Daecke of the Pennsylvania State 

 Agricultural Department at Harrisburg for the identification of 

 the flesh flies. Lucilia may be distinguished by the bright 

 metallic luster of the body, which is green. Calliphora has a 

 black thorax and an abdomen which is a deep metallic blue. 

 The species of Sarcophaga are grayish, and can usually be dis- 

 tinguished by the checkerboard pattern of gray and black squares 

 on the abdomen. 



