190 THE CANADIAN ENTOMOLOGIST 



In 1908f the same author described the nymph of another 

 species, L. vigilax. 



To these six species I can add two others, L. congener and L. 

 disjunctus, both of which I obtained on Vancouver Island during 

 the summer of 1913. 



These are all the species of Lestes known from Canada and 

 the Northern United States, except L. incequalis, although L. 

 eurinus has not been certainly reported from the Dominion. 



Of the nymphs of this genus reared by him, Professor Need- 

 ham says: "I find them well-nigh indistinguishable specifically. 

 Aside from slight and inconstant differences in size and a few very 

 minor structural characters, they are all alike." Certainly they 

 are a difficult group and can only be studied satisfactorily with an 

 abundance of material. Nevertheless, I believe that most, if not 

 all, of the species can be distinguished, provided both sexes are 

 present, though I must admit that it is very doubtful whether 

 single individuals, especially males, can be recognized with cer- 

 tainty in all cases. 



In regard to L. for cipatns and L. unguiadatus, I can say very 

 little, as I have seen no good specimens of either. These species 

 have therefore been omitted from the key that I give below, 

 though I have discussed them as far as the material before me 

 permits in the notes that follow. 



ffjll The key is based upon an examination of specimens kindly 

 lent me by Professor Needham, as well as material collected by 

 Mr. R. P. Wodehouse, of Toronto, and myself. 



Key to the Known Nymphs of Canadian Species of Lestes. 



A. Lateral spines present on abdominal segments 4- or 5-9; 

 labium, when closely applied to the ventral surface, reach- 

 ing to or beyond bases of hind coxae. 



B. Mentum of labium relatively stout in its proximal half, 

 its narrowest part being about one-third of the api- 

 cal breadth; lateral setae 4 or 5 congener. 



BB. Mentum of labium very slender in its proximal half, its 

 narrowest part being not more than one-fifth of the 

 apical breadth; lateral setae normally 3. 

 fBull. 124, N.Y. State Museum, 1908, p. 107. 



