DIPTERA 119 



A number of annoying and dangerous pests are members 

 of this order: house-flies which carry the germs of typhoid 

 fever; mosquitoes, which carry the germs of malaria and 

 yellow fever; tse-tse flies which carry the germs of sleeping 

 sickness; black flies and horse-flies, which bite painfully. 

 From the standpoint of public health, this is the most im- 

 portant order of insects. 



LESSON 11 

 Two-winged Flies 



WORK PROGRAM 



1. Raise some banana flies (Drosophila)* and get all 

 stages for observation. 



2. Collect house-flies in all stages. Trap, or poison, or 

 gather with a net some of the adult flies. Get the larvae and 

 pupae by raking over the stuff about the edges of a manure 

 pile at some ill-kept horse stable. 



3. Collect some horse-flies when they are pestering the 

 live stock in the pasture. 



4. Collect some robber flies with a net along the pas- 

 ture paths, where they will be found swiftly darting from 

 one resting place to another. 



* To raise Drosophila, crush an over-ripe banana, and leave it exposed 

 in a dish in warm weather. The little brown flies will find it and will lay 

 their eggs on it. Sprinkle a little earth dust over it to prevent growth of 

 molds. In about a week look for larvae and puparia. 



