20 



MISCELLANEOUS 0()TT(JN INSECTS. 



before April 1, the season being" an exceptional!}- eai'l}' one. The egg's 

 had been laid in the hard ground on the edges of tields and in fields 

 uncultivated during the present season. Young of the first instar 

 taken to the laboratoiy on April 23 molted April 25, May 10, May 23, 

 and May 30 and became adult on June 8. The habit of ascending a 



stalk of corn or weed 

 during the last molts is 

 illustrated in figure 9. 

 It was found exceedingly 

 difiicult to distinguish 

 the different instars by 

 any markings or by the 

 general size of individ- 

 uals, for in both these re- 

 spects different individ- 

 uals vai-y ver}^ greatly. 

 It was found by measur- 

 ing reared specimens, 

 however, that the length 

 of the hind tibite was 

 fairly constant for a 

 given instar, and this 

 proved true of a series 

 subsequently measured. 

 The length of the meta- 

 tibia is as follows: First 

 instar, 3-4 mm.; second 

 instar, 5-0 mm.; third 

 instar, 8-9 mm.; fourth 

 instar, 11-12 mm.; fifth 

 instar, 15-16 ram. These 

 are the measurements of 

 the cast skins, the meas- 

 urements in the case of 

 live or niounted speci- 

 mens being slightly less 

 in each instar. The time 

 of molting varied for dif- 

 ferent individuals and 

 was governed ])y the 

 amount of food available, so that no fixed dates can be given. In 1903, 

 in a local outbreak, the first three stages, mostly the second and third, 

 were found to occur on June 1. The development during these two 

 seasons probably illustrates the extreme dates of early and late develop- 

 ment for this latitude. 



Fig. 9. — M/lanoplus dijfferentiahs on corn leaves: adult i:i natural 

 position, upper figure; pupa skin below on right — n itural size 

 (author's illustration). 



