140 



SCHOOL ENTOMOLOGY 



all classed as one family, the Muscidce, of which the 

 House-fly is typical. This family is now considered as a 

 super-family and has been divided into several families. 

 Some of these it will be well to consider separately. 



The Tachina-flies (Tachinidce), are, for most part, para- 

 sitic on other insects. Their larvae attack grasshoppers, 

 many kinds of caterpillars and other 

 insect forms. The adults are like the 

 house-fly in general shape, but may 

 be stouter bodied, are often con- 

 siderably larger, and are usually 

 clothed with short, stout bristles, 

 especially prominent on the abdomen. 

 As a whole this group is beneficial. 



Flesh-flies (Sarcophagidce) , may be, 

 as larvae, either parasites or scaven- 

 gers. Many have habits similar to 

 the Tachinids while others feed on 

 decaying animal matter. Flesh-fly 

 eggs are often hatched within the 

 bodies of the females, the young 

 larvae being born alive. Flesh-flies 

 may be small, but are usually of 

 medium size or larger. 



Anthomyiids (Anthomyiidce) , are 

 flies smaller in size than the average 

 for the super-family. They resemble 



the common house-fly in conformation but may be more slen- 

 der and bristly. The maggots feed on decaying or living 

 vegetable matter. The ones attacking the roots of cab- 

 bage, onions, radishes and related crops are the most im- 

 portant forms. Dull colors prevail in this group. 



The Fruit-flies (Trypetidce) include numerous species 



3. 



4. 



FIG. 104. Parasitic 

 Diptera. Enlarged. 



1, Sheep bot-fly ((Estri- 

 da) ; 2, Louse-fly from hawk 

 (Hippoboscida) ; 3, "Sheep- 

 tick " (Hippoboscidce) ; 4, 

 Pupa of " Sheep-tick." 



