ENEMIES OF PLANTS. 295 



be well to preserve some of them in a solution of forma- 

 lin (made by mixing one part of formaldehyde, 40 per 

 cent., with 19 parts of water) for museum specimens. If 

 possible, have each stage of every species represented in 

 your collection of specimens. 



2. The Grasshopper. Find the three body divisions 

 head, thorax, and abdomen. 



THE HEAD. (i) Find the antenna; (slender feelers). 

 How many segments in each ? Draw. 



(2) Find the compound eyes. Examine a portion of one 

 under the low power of the microscope. What is the 

 general shape of these parts, or facets, of the eye ? Draw 

 several of them. In what direction can the grasshopper 

 see ? 



(3) How many ocelli, or simple eyes, do you find ? 



(4) MOUTH-PARTS. (a) Find the labrum, or upper lip. 

 Lift and remove it. Draw. 



(b) Note the mandibles, or true jaws, exposed by the 

 removal of the labrum. In what direction can you move 

 them ? Take out one. Draw. Does the grasshopper 

 obtain its food by biting or sucking ? 



(c] Find the labium, or lower lip. Remove it. Draw. 

 Is it a single appendage or two united ? 



(</) Look for the labial palpi attached to the labium. 

 How many segments in each palpus ? 



(e) Find the maxilhc, just in front of the labium. These 

 each consist of three parts united at the base ; the outer 

 one, the maxillary palpus; the middle one, a spoon- 

 shaped piece, the galea ; the inner piece, the lacinia, 

 (maxilla proper). Draw. 



(5) Take a fresh specimen and draw a front view of 

 the head, labeling all the parts.* 



* Every question in the above outline should be answered by 

 actual observations upon the insects. It may be that the student 

 will be better able to answer some of these questions, after hav- 

 ing made the laboratory study of the live insect. 



