4-H CLUB INSECT MANUAL 3 



threaten our plants and animals. Some of the diseases carried only 

 by insects have killed more people than have been killed in all wars. 

 However, to give the impression that all insects are pests would be 

 unfair, for most of them are of little or no importance and many, 

 such as the ground beetles, ladybeetles, wasps, and certain flies, are 

 beneficial, as they feed on insect pests. The honeybee makes honey 

 and beeswax, the silkworm makes silk, and many insects pollinate 

 plants. Insects also provide food for birds and fishes. 



This manual has been prepared so that young people may have a 

 better understanding of the lives and habits of many of the insects 

 and why they have been able to exist for so many centuries. Re- 

 member that even an insect may be justly entitled to a living and 

 do not destroy one wantonly or without good reason. We must, how- 

 ever, be able to protect ourselves against their taking too much of the 

 material we claim. The more of us there are who know our friends 

 and foes in the insect world, the better we shall be equipped to stand 

 our ground against the ravages of our greatest rivals, the insect pests. 



Part L— ACQUAINTANCE WITH INSECTS 



[Introduction to first-year work] 



What is this creature we call an insect, and how does it differ 

 from other forms of animal life? Insects are animals that in the 

 adult stage have an external skeleton and three definite body regions, 

 the head, thorax, and abdomen. They have three pairs of legs and 

 only one pair of antennae (feelers). They usually have compound 

 eyes and one or two pairs of wings. 



v y Antennae v 



* Head 

 Thorax 



Abdomen 



Figure 1. — External construction of an insect. 



Insects are adapted to a wide range of conditions. Some live 

 in the air and soil, some in plants or animals or their products, 

 and some in the water. Those that live out of the water breathe 

 through small openings along the sides of their bodies, and some 

 of those that live in the water are equipped with gills which enable 

 them to get their air from the water. 



There are more kinds of insects than of all other forms of animal 

 life put together. In fact, an entomologist found more than 1,000 

 different kinds in his small back yard in a suburb of New York City. 

 As there are about 700,000 different kinds of insects known to exist, 

 the need for some form of classification becomes apparent. Entomolo- 

 gists separate them into orders, families, genera, and species. (Each 

 of these classifications further divides the one preceding.) In this 

 manual no more can be done than help to acquaint the reader with 

 the more common orders. 



