140 CIVIC BIOLOGY 



The larvae that are infested with the parasites are usually 

 a paler green and are not so easily bent. Examine a number 

 of larvae, keeping in a closed vivarium those suspected of be- 

 ing parasitized. How many parasites are found in a single 

 larva ? The parasitic larvae begin to spin their cocoons as soon 

 as they emerge from their host. With the aid of a lens watch 

 this interesting process and note the length of time it takes to 

 complete the cocoons. 



Apanteles does not escape without its enemies. Two small 

 chalcis flies prey upon it, but thus far have not been effective 

 in checking its ravages upon the cabbage worm. 



