INSECT PESTS 257 



the tissues of their host, instinctively avoiding the vital parts 

 until, having reached maturity, they eat their way out to the 

 air and spin their small cocoons upon the body of their host. 

 Soon the perfect insect emerges and flies away to look for new 

 victims, leaving the parasitized host to die. The tomato worm 

 is very frequently parasitized, and a search in any large tomato 

 patch late in summer will probably reveal many worms cov- 

 ered with the tiny white cocoons of the parasite. 



PRACTICAL EXERCISES 



1. Make a list of the insects injurious to plants in your locality, 

 showing what crops they injure. Underscore the chewing insects in 

 the list. 



2. Place a cross before the names of insects in the preceding list 

 that have been found in the school garden. 



3. Make a list of the five most destructive insects in your locality and 

 indicate whether it is the larvae or perfect insect that does the damage. 



4. Make a collecting trip for insects, securing, if possible, eggs, 

 larvae, pupae, and perfect insects of the same species. This may be pos- 

 sible with the cabbage worm and a few others. Catch young crickets 

 or grasshoppers and compare with mature forms. 



5. Search tomato vines for parasitized tomato worms. Similarly, 

 parasitized worms may be found on grapevines, the box elder, the apple, 

 and many others. 



6. Collect and label samples of all of the poisons used for combat- 

 ing insects. 



7. Examine collections of insects for the dragon flies, ladybugs, 

 ichneumon flies, ant lions, and other insects that prey upon harmful 

 species. 



References 



Bailey, "Manual of Gardening." 

 Fernow, "Care of Trees." 



Farmers' Bulletins 



99. Insects Injurious to Shade Trees. 

 127. Important Insecticides. 

 146. Insecticides and Fungicides. 

 155. How Insects affect the Health in Rural Districts. 

 196. Usefulness of the Common Toad. 



