2l8 NATURE STUDY. 



intended for trained entomologists, and the boys and girls 

 must be content for the most part with pinning their flies in 

 their boxes without classifying them. 



Nevertheless, something can be done, even with flies and 

 by children. 



One may feel sure about the house-fly. Notice the shape 

 of its body, the size and shape of its head, and the relative 

 length of its legs. This familiar fly belongs to the family 

 Muscidse, and if other flies that resemble it are placed in 

 the same family there will not be so many mistakes as one 

 might expect. 



About the bee-flies there will be no mistake at all. 

 They are to be found in and beside roadways, especially 

 in springtime. They have a way of hovering for some 

 time in one place and then moving to another a few feet 

 away, where they will pause in the air again. They are 

 more difl&cult to catch than most flies, and will often give 

 the collector a lively chase. The bee-fly, when on the 

 wing, looks a little like a small bumble-bee, and when 

 captured it will be found to have a small head and a very 

 long and slender proboscis or tongue. They are to be la- 

 beled Bombylidse. 



The robber-flies are quite abundant in the fields, and 

 are mostly of large size. They have long, slender abdo- 

 mens and strong wings, but the most marked characteris- 

 tic is the long, pointed proboscis, with which the robber- 

 fly sucks the life out of its victims. It not only catches 

 other flies, but is able to destroy large insects, as bumble- 

 bees, tiger-beetles, butterflies and dragon-flies. 



It is a gruesome but not uncommon sight to see a but- 

 terfly, as one of the yellows or a copper or a fritillary, sail- 

 ing along in a straight line without moving a wing. The 

 contrast between this enforced flight and its usual, grace- 

 ful, zigzag movement is very striking. It has been seized 

 by a robber-fly, which is greedily sucking out its juices 



