THE LOCUST 

 Phylum Arthropoda Class Insecta 



I. BEHAVIOR AND EXTERNAL FEATURES 



Exercise 1. — General Activities. 



(a) Grasshoppers and locusts are the most common representatives 

 of the Order Orthoptera. The large lubber grasshoppers are very 

 favorable for study, but any good-sized local species can be used. 

 Living individuals should be observed in glass jars containing grass 

 and covered with a screen. How are the legs used in walking and 

 jumping? Respiratory openings will be seen along the sides of the 

 abdomen. Observe and time the intervals between the respiratory 

 movements. Note the color and its distribution. Does this suggest 

 an adaptation of the animal to its habitat? Offer bits of green vege- 

 tation to the animals and try to observe their mode of feeding. Touch 

 the "feelers" of the head with a long piece of glass tubing having a 

 plug of absorbent cotton in the end, and observe the sensitiveness of 

 these organs as compared with other parts of the body. Moisten the 

 absorbent cotton with some strong-smelling fluid, and bring it near a 

 feeler without touching. Are these organs chemoreceptors? Can you 

 determine whether other parts of the body have a similar function? 

 Remove a specimen from the jar and examine the parts more closely. 

 Note the "molasses" which is regurgitated from the mouth; this is a 

 digestive fluid mingled with food. If a good-sized drop can be col- 

 lected from one or more specimens and placed upon a slide, put a bit 

 of fresh vegetation in this drop and note the result before the fluid 

 evaporates. ■ What may be the significance of this habit of regurgi- 

 tating the contents of the digestive tract? If you have time, devise 

 experiments to determine whether temperature or sensations com- 

 parable to fear in the higher animals influence the rate of respiratory 

 movements. 



Exercise 2. — External Features. 



(b) The body has three main divisions: the head, thorax, and 

 abdomen. Each of these divisions is made up of a number of more 

 or less well-defined rings, called somites. The outer covering, or 



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