1 86 PHINEAS W. WHITING. 



I have frequently found in my cultures imperfectly formed 

 pupae, sometimes misshapen and sometimes of normal form but 

 with a soft covering. These have given rise in a few cases to 

 undersized but normally formed flies, which lived as long as the 

 full-sized individuals. In the majority of instances, however, 

 the flies emerging were of normal size insofar as the chitinous 

 parts of the body were concerned, but the abdomens appeared 

 shrunken, the wings expanded only imperfectly, and the pig- 

 mentation failed to take on its customary brilliancy, remaining 

 dull and opaque. This type of fly has also frequently appeared 

 from pupa? apparently normal. In the case of Lucilice which 

 vary from a brilliant metallic green or greenish blue to a bright 

 copper color becoming duller with age, the imperfectly formed 

 flies resembled senescent individuals, being a dull coppery red. 

 In the other larger species which are normally dark metallic 

 blue with pollen that varies in amount in the different species 

 and in the different individuals of the same species, the imperfectly 

 expanded flies were dark blue in color without polish. That 

 these imperfectly formed flies were hindered from normal develop- 

 ment by drying of the pupae, while small flies are produced from 

 underfed larvae might seem a reasonable explanation were it not 



access, no distinction being made between the species of Lucilia. The relative 

 abundance of L. sericata in the vicinity of Boston is especially to be observed where 

 flies are crowded about a food supply in large numbers in which case it is only rarely 

 that L. ccesar is taken. I have collected thousands of flies in the vicinity of the 

 garbage scow, Boston, and at meat near the Bussey Institution, Forest Hills, and 

 have found that less than one per cent, have been L. ccesar, while L. sylvarum has 

 never been taken in such situations. At a very short distance from the Bussey 

 Institution, however, where flies are relatively much fewer, L. ccesar and L. sylvarum 

 have equalled and even surpassed L. sericata in numbers. I have never taken them, 

 however, in any abundance. It is possible that L. ccesar may be more abundant in 

 the region of the Great Lakes where Herms's work was done. 



Calliphora erythrocephala is common about Boston all through the summer 

 months while viridescens and vomitoria are rarely seen except in the spring and fall. 

 Cynomyia cadaverina occurs only in the spring and fall and seems entirely to dis- 

 appear during the summer. That these variations in frequency are entirely due 

 to temperature and that there is no necessary periodicity in the breeding habits of 

 the flies is evidenced by the facts that the forms disappearing during the summer 

 still continue to breed farther north and that any of the species may be bred through- 

 out the year by the proper regulation of temperature conditions. Lucilice and 

 Calliphorce have been bred throughout the winter at Cambridge by Dr. A. O. Gross 

 and Calliphorce and Cynomyia have been bred during the entire year at Forest 

 Hills by myself. 



