1 6 CONNECTICUT GEOL. AND NAT. HIST. SURVEY [Bull. 



are especially liable to attack, being exposed above the water line 

 (Needham 1903). 



Spiders are confirmed enemies of most insects and have been 

 found to capture dragonflies. 



Several species of water mites (Hydrachnidae) are often found 

 clinging to nymphs and adults, especially damsel flies. They 

 attach themselves to the nymph while young, crawl from nymph 

 to adult at emergence, and gain the water again at oviposition. 

 Little or no real harm is experienced by the dragonfly, and the 

 mites seem to hang on mainly for the ride, obtaining, of course, 

 free transportation from pond to pond. Only one case has been 

 reported (Wilson 191 7- 18, p. 225) in which these mites were 

 harmful to the host. However, adults have been observed by the 

 writer so heavily laden with mites that they were unable to rise 

 from the water. A red mite is also said to destroy the eggs of 

 Odonata (Lamborn 1890, p. 50). 



The fresh water hydra (H. fusca) was found by Wilson to 

 devour recently hatched nymphs (Wilson 191 7- 18, p. 210). 



Nematodes (gregarines) are known to inhabit the alimentary 

 canal of dragonflies, but probably do little harm. 



Several species of fungi and algae may be found growing upon 

 the nymphs, but usually do little harm. The saprolegnias are 

 sometimes injurious and even fatal, especially to crippled or feeble 

 nymphs. 



A filaria and a frog-lung fluke have been found in nymphs, 

 but have not been reported from America. Likewise the giant 

 sundew of Australia (Tillyard 191 7, p. 329) is said to capture 

 many damsel flies, but our American sundews are certainly not 

 capable of duplicating this performance because of their small size. 



General Characters of the Odonata 



The Odonata include insects, the adults of which have biting 

 mouth parts and net-veined wings. The legs are weak and used 

 mainly for support when at rest, though sometimes for grasping 

 and holding prey. 



All species have an incomplete metamorphosis, the aquatic nymph 

 developing by successive stages until the last instar, when the 

 insect leaves the water and the adult emerges. The transforma- 

 tion in changing from nymph to adult is almost as great as we 

 find in orders with complete metamorphosis, but there is no true 

 pupal stage and they are known as hemimetabolous (Comstock, 

 1920, p. 178). 



Comstock has proposed the term naiad for the aquatic stages 

 of Odonata, a term which has advantages. For example, the 

 change from aquatic to aerial life necessitates much greater changes 



