290 



State Horticultural Societw 



We also have a great many beneficial flies, especially certain Tach- 

 ina-flies, one of which is shown in its various stages in Fig. 16, and 



Fig. 16. Tacbina fly ; larva, pupa, eggs. 



also some of the eggs placed on the forepart of a larva. Some of them 

 are larger than a house-fly, and some of them not so large, resembling a 

 house-fly or blow-fly to a great extent. These flies do a great deal of 

 good by depositing their eggs upon the bodies of various larvae or cater- 

 pillars. The grubs, when they hatch, bore their way into the body of the 

 host larva and feed upon his tissues, usually not killing the larva, but 

 weakening it so that it is usually able to transform to the pupa stage, but 

 not to the adult condition. Instead of the adult of the host larva appear- 

 ing, we have the adult of the Tachina-fly hatching out. 



But above all of the beneficial insects which I have just called your 

 attention to, the group known as the Ichneumon-flies is pre-eminent in 

 this matter of holding in check various insects. We have thousands of 

 species of these Ichneumon-flies, a large one of which is shown in Fig. 

 17. Some of these insects are extremely small, others are even larger 



Fig. 17. 



than the figure I have given. You will notice on the caudal end of the 

 body a little, short "sting." By means of this "sting" the various Ich- 

 neumon-fiies deposit their eggs within the eggs, larvae, pupae, the adult 

 stages of practically all kinds of insects, the result being that instead of 

 the original insect maturing, we have emerging from the dead insect one 

 or more of these Ichneumon-flies, as the case may be. These are the in- 

 sects that keep the great bulk of our injurious insects in check, and these 



