FAMILY MUSCIDM 



281 



during even a nortliern summer, probably from six to eight 

 being common. 



For the destruction of the larvse, which is probably the 

 most effective way of preventing damage, two principles 

 have been established. The first involves the killing of the 

 maggots by introduction of some destructive agent; the 

 other, the prevention of their maturing by the rapid drying 



Fjg. 225. — ^Horn fly {Hemalobia serrala): a, egg; b, larva; c, puparium; 

 d, adult in biting position. All enlarged. (From Riley and Howard.) 



of the mass of dung which supplies their food. The use of 

 lime, as originally suggested in Insect Life, is a very effective 

 plan, and where not prohibited by expense, should be generally 

 adopted. Prof. Smith's suggestion to spread out the drop- 

 pings of manure so that they may dry rapidly is applicable 

 during dry weather and in some localities is accomplished by 

 drawing brush across the fields, a method which must 



