INSECTS AND PLANT DISEASES 81 



When the crop is troubled by both insects and plant 

 diseases the remedies may be mixed and applied at a 

 single spraying. A good spraying pump costs from 

 two dollars up. The recipes for and the average cost 

 of the mixtures are given below. 



Experimental Study of Insects. 



Insects may be captured with a net made of mos- 

 quito bar attached to a hoop at the end of a long 

 stick. Before examination they should be killed in a 

 "cyanide bottle." This bottle is prepared as follows: 

 Into a large-mouthed bottle, provided with a cork, put 

 a small piece of potassium cyanide, a very deadly 

 poison. Cover this poison with a layer of plaster of 

 paris and allow it to harden. Always keep the bottle 

 tightly corked. Shake the live insect from the net into 

 this bottle and it will soon be ready for examination. 



1. Study a wasp, a bee, or a grasshopper. Note 

 the three parts of its body, the head, the thorax or 

 middle section, and the large hind section, or abdomen. 

 Also note that the abdomen is made up of smaller, 

 ring-like sections. From this can you see why they 

 are called insects? Watch the abdomen of a live in- 

 sect closely and see it expand and contract as the in- 

 sect breathes. 



2. How many legs has an insect? Are they al- 

 ways attached to the same part of the body ? How are 

 the legs jointed? 



3. Many insects are wingless; some have a single 

 pair of wings and others have two pairs of wings. 



