10 BULLETIN 1016, TJ. S. DEPARTMENT OE AGRICULTURE. 
had only five stages instead of six. The specimens used for the 
figures in this paper all had fed for some time after casting their 
last molt. In most cases the specimens were preserved for three, 
but in some cases for only two days after molting and during this 
period the individual was permitted to feed. Illustrations of speci- 
mens which have just molted and have not fed, or specimens about 
to molt, are likely to be misleading, as they are not normal repre- 
sentatives of the stage desired. Very often the color pattern of a 
specimen fades considerably just before molting, and if drawings 
are made at that time the color pattern for that instar will be 
wrongly recorded. 
The nymphs of the chinch bug during the molting period feed 
very little, and their color pattern fades toward the close of the 
period.' This fading is due to the 
loosening of the transparent cuticular 
layer, which is about to be cast. The 
darker color pattern of the succeeding" 
instar can often be seen through the 
thin layer. 
One nymph was caught in the act of 
casting its skin. When first observed 
it had already freed part of the ab- 
fig. i. — The chinch hug (BKssus domen and thorax. It then drew its- 
leucoptertis) : Cluster of eggs, -, , , • -, i • „-i 
showing tubercles at the trun- legs out one at a time and by a jerky 
cated or blunt ends. Greatly motion of the abdomen freed itself 
enlarged - entirely from the old skin. The 
nymph utilized its last pair of legs to push off the skin from the tip 
of the abdomen. 
DESCRIPTION OF THE EGG AND NYMPHAL STAGES. 
A description of the egg (fig. 1) and nymphal stages is given be- 
low. It does not seem necessary to describe the adult or the sixth 
instar (fig. 2, /), but a brief discussion of the sexual differences 
in the adult stage is included. It seems important that the sexual 
differences be known in order to facilitate biological work on this 
insect. 
EGG. 
The egg is elongate ovate, slightly rehiform in shape, rounded at one end 
and truncate at the other. The truncate end is supplied with from three to 
five, usually four, tubercles 0.1 millimeter in length; opaque white in color 
when just deposited, turning amber in a few days and deep red several days 
before hatching. Just prior to hatching the embryo shows through the chorion 
which is smooth, shiny, and somewhat iridescent. 
Length, 0.858 mm.; width, 0.308 mm. 
