558 HOWARD 



the Larva? of Muscidce ' (Berliner Entomolog. Zeitschrift, Bd. 

 XXXI, 1887, heft I, pp. 17 to 28). Professor Porchinski's 

 paper contains a series of important observations, and, accord- 

 ing to Osten Sacken, " illustrates the wonderful power of adap- 

 tation of these larvae to their environment, an adaptation which, 

 in a certain measure, destroys the parallelism which we natur- 

 ally expect to exist between the systematic characters of larva 

 and imago. * * * Distantly related species, belonging to dif- 

 ferent genera, issue from larvee almost undistinguishable from 

 each other. Again, closely related and almost undistinguish- 

 able imagos, species of the same genus, differ in their ovipo- 

 sition (size and number of eggs), and their larvce follow a dif- 

 ferent law of development (as to the degree of maturity the 

 larva reaches within the body of the mother and the number of 

 stages of development it passes through)." 



Interesting generalizations might be made from the present 

 studies, but such work is foreign to the immediate purpose of 

 the investigation. In examining the specimens, however, it will 

 be noticed that there are three predominant types of flies, 

 namely the medium sized gray, somewhat striped flies of the 

 Musca doniestica type, the metallic greenbottle or bluebottle 

 flies, and the small, dark brown or black flies of the Homalo- 

 myia type. Several species, for example, belonging to different 

 families, so closely resemble Musca domestica that even a trained 

 entomologist cannot distinguish them without a close study of 

 structural characters. This fact accounts for a very general 

 popular misunderstanding as to the specific habits of .Musca 

 domestica. 



DETAILED CONSIDERATION OF THE DIPTERA STUDIED. 



Family CHIRONOMID^. 



The insects of this famil}^ possess almost no importance from 

 the standpoint of this article. They are small slender midges 

 or gnats rather closely resembling mosquitoes and flying oc- 

 casionally in enormous swarms. The larvae are aquatic or are 

 found on moist sappy places on tree trunks, or occur in the 

 earth or in dung. The adults are not especially attracted to 

 any one class of substances but frequent moist places. 



