THE ECONOMIC BIOLOGY OF INVERTEBRATES 479 



Crustacea. 



1. Lobster, crab, shrimp, etc., for food. 



2. Small forms for fish food, barnacles harmful. 



Acerata. 



1. Spiders useful in killing flies, etc. 



2. Scorpions dangerous, but not fatal. 



3. Daddy-long-legs feeds on plant lice. 



4. Mites and ticks, parasitic and harmful to man and animals. 



Harmful activities. 

 Insects. 



1. Destroy crops. 3. Injure domestic animals. 



2. Transmit disease. 4. Destroy clothing, buildings. 



5. Annoy and injure man. 



Useful activities. 



1. Pollenation. 5. Furnish honey and wax. 



2. Scavengers. 6. Dyes. 



3. Kill injurious insects. 7. Shellac. 



4. Silk. 8. Ink material. 



Common Injurious Insects. 

 Fruit tree pests. 



Tent caterpillar. 



Codlin moth. 



Scale insects. 

 Shade tree pests. 



Tussock moth. 



Cottony maple scale. 



Various "borers." 

 Garden pests. 



Potato "bug." 



Squash bug. 



Cabbage "worm." 

 Household pests. 



Flies and mosquitoes. 



Buffalo carpet beetle. 



Cockroaches, croton bugs. 



Clothes' moths. 

 Treatment. 



Sucking insects with contact poisons. 



Eating insects with digestive poisons. 

 Useful forms. 



Lady bug. 



Thalessa (an ichneumon fly). 



Carrion beetles. 



