296 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.49. 



seldom fomid far from the weedy banks of a pond or stream and 

 both are fomad about either alkalme ponds or fresh rmming water. 

 However, cervula seldom occurs abundantly except around alkaline 

 ponds. 



ISCHNURA CERVULA Selys. 

 Figs. 77-80, 87-91, 94-100, 106-109, 117-121, 127-132. 



While occuring from early spring till heavy frosts in the autumn, 

 Ischnura cervula reaches its greatest abundance during the months 

 of May and June. About rumiing water it is scarce, in such places 

 choosing the more stagnant spring laterals and side ponds. As with 

 the other species of the genus, it is seldom found over the water or 

 on land far from the moist banks of a pond or stream. 



It emerges in the daytime, usually between 9 and 11 o'clock in the 

 morning, when it can sometimes be found emerging in swarms. At 

 such times the nymphs can be seen swarming to the bank with a 

 tadpole-like wriggling motion. They usually wait about 15 minutes 

 after crawling from the water imtil they dry and the back splits. 

 A half hour later they are on the wing. This species has, especially 

 during imagmal life, the Lestes habit of hanging among aquatic 

 vegetation and dodging anipng the reed stems to avoid capture. 



Copulation takes place with the couple moving about among the 

 vegetation or at rest on some leaf, and lasts for many minutes. 



In oviposition the female, usually unaccompanied by the male, 

 deposits her eggs in any vegetable substance under the surface of 

 the water which is soft enough to be pierced by her ovipositor, 

 usually the stems of aquatic plants, but sometimes she will alight on 

 the surface of a floating mass of filamentous algae and oviposit in 

 the tangle of algal filaments. Usually the abdomen is bent U-shaped 

 and the wings are loosely folded as in copulation, but occasionally 

 she assumes the poses of perparva, with the wings tightly folded. 

 (See figs. 87 and 88.) 



I have three pairs which were killed while in copulation. In one, 

 the hold of the male on the prothorax of the female is still retained. 

 Figure 89 shows how the parts fit together. The concave apical 

 edges of the inferior appendages of the male rest on the anterior 

 surface of the posterior lobe, each at about the base of the pencil of 

 hairs. The inferior apical points of the superior appendages rest 

 under the roof-shaped posterior lobe, while the angle of the superiors 

 rests on the mesostigmal lamina. Probably in life the V-shaped 

 prolongation of the doi-sum of segment 10 rests on the mesothoracic 

 carina of the female. In tliis dried pair it is slightly raised. 



In copulation, segments 8 and 9 of the female are opposed to seg- 

 ment 2 of the male. The very heavy penis seems to be the sole 

 clasping organ, as the "anterior hamules" fold inward during copu- 



