74 DIPTERA. 



Puucin/E {Fleas). 



This group constitutes the order Aphaniptera of 

 Kirby, VVestwood, and many other writers. For char- 

 acters, see 1,388; 14, II., 488. 



The Human-flea, Pulcx irritans Linn., is an example 

 of this family. 



SVRPHIDyK. 



Many species of this family are remarkable for their 

 resemblance either to wasps, or bees. They hover 

 about flowers and extract nectar from them. The 

 larvse of many species are very beneficial, as they feed 

 upon Plant-lice. Some live in decaying wood ; others 

 live parasitically in the nests of bees ; a few are aquatic. 



See specimens of Microdon globosus Fab., larva, pu- 

 parum and adult ; Rat-tailed Maggots, Eristalis trans- 

 7>crsns VVied., larva and adult ; and Volucclla cvccta 

 Walk. Note resemblance of Volucella to a bee. 



Discussion of mimicry. (See Wallace on Natural 

 Selection, p. 75, and 3, III., 159). Examine carefully 

 specimens of the following insects, and note resem- 

 blances. Volucella (Dip.) and small worker Humble- 

 bees (Hym.) ; Laphria (Dip.) and Bombus (Hym.) 

 Spilomyia (Dip.) and Vespa (Hym); Limenitis disip- 

 pus Godt. (Lep. Nymphalid;u) and Danais archippus 

 Fabs. (Lep. Danaida;). 



OsSTRID/R {Bot-flies, Breeze-flies.) 

 " In these flies, so interesting in their habits, the 

 body is stout, hairy, like the Humble bees, and they are 

 easily recognized by having the opening of the mouth 



