Families Micropzidae, Sepsidae, Psilidae and Diopsidae 



cipally as a cheese pest, and it is a matter of common observa- 

 tion that the mother fly seems to prefer the older and richer 

 cheeses in which to deposit her eggs. Her taste is excellent, 

 and, while it is a fair thing to say that skippery cheese is 

 usually the best, it will hardly do to support the conclusion 

 that it is good because it is skippery, although this con- 

 clusion is current among a certain class of cheese-eaters. 

 Readers of this will be reminded of the inimitable scene in the 

 Erasmus Inn, described by Charles Reade in "The Cloister and 

 the Hearth." 



The flies of the family Psilidae are a little stouter and shorter 

 than the Micropezids, and are sometimes light in color, though 

 generally dark. The metamorphoses of very few of them are 

 known. Some occur in the stems of plants; others are found in 

 the roots of carrots and cabbages, and the flies themselves are 

 seen commonly sitting upon the leaves of bushes and low- 

 growing plants. 



The Diopsidae are remarkable from their very curious heads. 

 The head is greatly broadened, with the eyes at the extremities, 

 and the eye-portion is swollen. In some tropical species this 

 feature becomes so exaggerated that the insect looks almost as if 

 it carried bicycle handle bars on its head. They are small black 

 flies, usually stouter than those of the groups which we have 

 just mentioned, and they are found in shady wooded places. 



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