DRAGONFLY AND DAMSELFLY NYMPHS 



(Materials: Mason jars and jar lids, carmine suspension.) 



Classification, — Phylum Arthropoda, Class Insecta, Order 

 Odonata. 



Distinguish two kinds of odonate nymphs, those with slender 

 bodies and three flat plate-like gills at the posterior end of the 

 abdomen ; and those which lack these plates and are stout bodied. 

 The ones with the plate-like gills are called ''damselfly" nymphs 

 and the stout bodied ones are "dragonfly" nymj^hs, though the 

 name ' ' dragonfly ' ' is also often used as a general term for all in- 

 sects of the Order Odonata. 



Keep your specimens under water. A Mason jar lid makes 

 a convenient dish. Invert the jar and place the lid containing 

 the specimen on the bottom of it. This brings the specimen to 

 a convenient height for study with a hand lens. 



I. Dragonfly Nymph 



1. Describe the resting habits and position of nymphs in an 

 aquarium. Where do they usually rest ? Notes required. 



2. Do the nymphs ever feign death or ' ' play possum ? " If 

 so, under what conditions? Have you ever seen this habit in 

 other animals 1 What kinds 1 Notes required. 



3. Place a large nymph in a Mason fruit jar lid. Place a 

 small drop of carmine suspension near the posterior end of the 

 abdomen of a resting nymph and describe the result. Repeat the 

 experiment until you are sure of the results. In connection with 

 this experiment remember that carmine is inert and is used 

 merely to show the presence of and direction of water currents 

 State your observations. What conclusions may be drawn from 

 this experiment ? Notes required. 



4. Describe the methods of locomotion of the live animal. 

 How many different methods? Describe each. Notes required. 



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