i86 FARM FRIENDS AND FARM FOES 



OBSERVATIONS FOR PUPILS 



American Tent Caterpillar 



1 . Collect a few nearly full-grown caterpillars from the nests late in 

 spring and keep in vivaria, feeding as necessary. See how many of 

 them are killed by parasites. 



2. Collect from the nests any cocoons that may be made in them. 

 These are pretty sure to be infested by parasites. See how many sorts 

 of flies come from them. 



3. See if you can find in the nests peculiar shrunken caterpillar skins 

 with a cocoon inside. Keep these and rear the parasites. 



4. Look up these references : — 



Stories of Insect Life, First Series, pages lo-ii. Nature Biographies, pages 22-34. 



Cabbage Butterfly 



I.- Early in spring look on boards, fences, or the sides of build- 

 ings near gardens where cabbages have been planted, for masses of the 

 small yellow cocoons of microgaster parasites. Keep such cocoons in 

 dosed vials or boxes to rear the flies. If two kinds of flies emerge, the 

 larger black ones will be the microgaster flies, which are the primary 

 parasites, and the smaller flies will be secondary parasites. 



2. Early in spring collect a number of the cabbage butterfly chrysalids 

 that may be found in boards and fences near old cabbage patches. 

 Keep in small, vivaria. From some of them you will be likely to rear 

 hundreds if not thousands of small chalcid flies. Count the number 

 from one chrysalis. Let the flies escape to continue their good work. 



3. In autumn collect a number of cabbage worms. They may gen- 

 erally be found abundantly on cabbages. Keep them in vivaria. See 

 how many are killed by parasites. 



4. Read The Insect Book, pages 57-60 ; Stories of Insect Life, First 

 Series, pages 16-17. 



Fall Web-worm 



1. Early in autumn collect a score or more nearly full-grown fall 

 web-worms and place in vivaria. Several of them are likely to be killed 

 by parasites. 



2. Find cocoons of the fall web-worm in which external parasites are 

 preying on the larvse. 



3. Read The Insect Book, pages 64-68. 



