FAMILIES MICROPEZID/E, SEPSID/E, 

 PSILID/E AND THOPSIDAE. 



The Micropezid flies are slender, dark creatures of a good 

 size, with a few spots on the wings. They are rather awkward 

 in shape, their legs being long, and they are not common. 

 Nothing is known of their metamorphoses, but they are cap- 

 tured upon decaying and foul vegetable and animal matter. 



The Sepsidae comprise a series of small, frequently shining 

 black flies, of rather slender form, which breed, as a rule, in 

 decaying vegetable material or in dung. The little shining black 



Fig. 102. — Sepsis violacea. (Author's illustration.) 



species of the genus Piophila, however, breed in cheese, ham 

 fat, and in other fatty or spoiled and decaying animal matter. 

 The little maggot known as the " cheese skipper" is the larva of 

 Piophila casei Linn. This insect frequently does great damage 

 in packing establishments. The eggs are laid in compact clusters 

 of from five to fifteen, or are scattered singly. Each female lays 

 about thirty eggs. The egg is white, slender, slightly curved, 

 one millimeter long, and hatches in thirty-six hours. The larva 



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