branch: biology of KANSAS MEMBRACID^. 83 



and adult forms. In this first instar, it is interesting to note 

 that there is an articulation between this segment and the 

 head. The head, which is dark and shiny, is extremely large 

 in proportion to the body; in fact, it is larger in a line from 

 back to front in dorsal aspect than in the adult forms. (Fig. 

 58, pi. XVI.) 



The mouth parts are enlarged out of all normal proportion, 

 the distal end of the beak reaching to the end of the sixth 

 abdominal ring. (See fig. 57, pi. XVI.) The ocelli are found 

 in about the normal position. 



On the twelfth day (counting from the date of oviposition 

 and on the third day of the life of the nymph), July 12, oc- 

 curs the first moult. In this second instar the enlargement 

 of the prothorax takes on a shape similar to that in the adult 

 form, except that it does not extend back over the abdomen, 

 but it does extend far enough to cover the mesothorax. The 

 prothorax bears the shovel-like horn and the notch which 

 forms the dorsal hump. The head is reduced in size in this 

 instar. The second, third, fourth, fifth, sixth, seventh and 

 ninth abdominal segments bear two dorsal hirsute spines, the 

 lateral ones having disappeared. The third, fourth and fifth 

 segments are marked with dark dorsally and about half way 

 down the lateral face. The nymph, in the second instar, meas- 

 ures 2i/> mm. in length. 



A curious fact noticed is, that in the nymphal stages the 

 forms do not exhibit any jumping power, but run very rapidly. 

 ■\Vhen four days old the measurement is 3 mm., but they have 

 not moulted. 



On the fifth day after hatching (July 14) the second moult 

 occurs. In this third instar a differentiation of color is 

 observed. A number of the forms are dark with black "hoods," 

 while others are light with tan hoods. Upon further observa- 

 tions, this color difference seems to be the indication of the 

 sex to be formed in the adult stage, the dark ones emerging 

 as males and the light ones as females. In this instar also the 

 wing pads appear. (See fig. 59, pi. XVI.) When nine days 

 old (July 18) the third moult occurs. In this fourth instar 

 we have the stage which is comparable to the pupa stage in 

 forms having complete metamorphosis. In figure 60, plate 

 XVI, is seen the "pupa," with the prothoracic enlargement 

 spilt open ready for the emergence of the adult. This emer- 



