76 



OUll FARM CROPS. 



remain through the winter in their pellucid skins, and do 

 not produce flies until the following summer. 



The natural history of this little fly is very interesting, 

 and one which every one should read, as we therein see 

 a marked case of the beautiful provision made by Provi- 

 dence to prevent the undue multiplication of a species 

 capable of inflicting such injury upon one of the food 

 plants of man. The reproduction of the species is con- 

 trolled within certain limits, by the existence of an ich- 

 neumon fly (the Platygaster Tipulce), which may be seen 



y; 



1. Infected floret. 2. Larva, natural size; and 3, magnified. 4. Pupa, 

 natural size ; 5, magnified ; 6, attached to grain. 9 and 10. Midge, natural 

 size and magnified. 11 and 14. Ichneumon fly, natural size and magnified. 

 13 and 12. Macroglenes penetrans, natural size and magnified. 



running over the wheat ears, seeking out the midge every- 

 where, for the purpose of depositing its own eggs in the 

 midge's body, and thus restrains an increase which would 

 otherwise so prejudicially affect our crops. The Macro- 

 glenes penetrans also assists in checking the ravages of 

 the midges. 



