Vol. XXviii] ENTOMOLOGICAL NEWS 179 



second instar nymph would be approximately 1.25 times that 

 of the first instar nymph. 



Upon attaining the adult stage a sexual dimorphism becomes 

 apparent. Besides the structural differences of the genitalia, 

 the anterior legs of the male possess on the inner faces of the 

 femora and tibia peculiar stridular areas. 



The tibial structure is borne on the inner face of a promi- 

 nence, which is formed by the elevation of the inner angle or 

 margin of the tibia near its base into a thin but elongate spur. 

 This spur is lacking in the female and not discovered in the 

 nymphs. (See pi. XIII, Figs. 5 and 6.) 



THE DEVELOPMENTAL CHANGES. 



Head. The notocephalic margins of the eyes which are near together 

 and nearly parallel in the adult are relatively much farther apart in the 

 first instar nymph. In the newly hatched bug, the distance at synthlip- 

 sis is nearly 1-3 (one-third) width of head with the margins of the 

 eyes diverging broadly to the vertex. As the development proceeds 

 from instar to instar the eyes are brought nearer and nearer to their 

 relations in the adult where the synthlipsis is reduced to about 7.14% 

 of the width of the head. 







The beak is four-segmented and the antennae of the nymphs have 

 much the form of those in the adults. 



Legs. The general form as in the adult. The tarsi of all the legs 

 one-segmented and terminated by two claws. (The tarsi of the adults 

 are two-segmented and end in two claws.) 



Wings. The wing-pads are very inconspicuous even in the later 

 nymphal instars. By the third instar the pads appear on the antero- 

 ventral margins of the mesothorax as little flaps, the distal ends of 

 which reach a position on a line with the trochanter of the fore leg 

 when flexed. In the fourth instar they arc much larger, the apices at- 

 taining to a position on a line with the distal end of the mesothoracic 

 tibiae when the limb is flexed. In the fifth instar they are still closely 

 applied to the side of the thorax, but the tips of the more opaque pads 

 reach a point on a line with the distal ends of the hind coxae. 



HABITS OF THE SPECIES. 



Bncnoa margaritacca is the common representative of its 

 genus in the ponds and pools of eastern Kansas. It appears 

 to prefer the open water and is in much better equilibrium in 

 its watery world than the Notoncctae. 



Individuals of this species may be seen in large numbers 



