11 
has more direct influence than air temperature does in bringing about 
variations in the life history of a subterranean insect like the changa. 
The cage used in procuring data on egg laying was a rectangular 
wooden sash, 24 inches long, 8 inches wide, and 1 inch high. Lateral 
grooves inside the sash, in which panes of glass could be run, per- 
mitted the depth of soil placed between the panes to be regulated. 
With a half inch of earth, the depth found to be most satisfactory, the 
runways of the adults were always in sight and could be observed 
without removing the glass. The cages were placed horizontally 
and covered with a dark cloth to simulate natural conditions. Sliced 
potato was at first used as food, but later sprouted corn was sub- 
stituted. 
As eggs were laid they were protected from the parent changas by 
a zinc ring the height of the space between the panes. It is possible 
that the egg stage was affected by keeping the eggs in a location so 
much more liable to temperature changes than the natural egg cham- 
ber located some inches below the surface of the ground. However, 
incubation of eggs in the cages seemed to be influenced as much by 
the moisture content of the surrounding soil as by the air tempera- 
ture. It was impossible to collect exact data on the relation of length 
of incubation to soil-moisture content. 
The young changas upon hatching were isolated in shell vials 5 
inches long and 1 inch in diameter, which contained sand and 
sprouted corn. The changas were measured and transferred to vials 
of fresh food once a week until arriving at the fourth instar. After 
the fourth instar they were transferred to 250-cubic-centimeter Erlen- 
meyer flasks containing earth and sprouted corn. All changas from 
the fourth instar on were measured and transferred to fresh flasks 
every second day. Moisture conditions in vials and flasks were kept 
as near the optimum as possible. 
Individuals reared from the egg were noticeably smaller when the 
final instar was reached than those taken in the field in the fourth 
instar or later and brought to the adult stage. The former indi- 
viduals averaged about 3 millimeters less in body length and about 
1.5 millimeters shorter in medial length of the pronotum. 
It is not probable that the unnatural conditions under which the 
rearing work was done affected the length of the developmental 
stages very seriously, for nearly mature changas taken in the field and 
brought through to the adult stage in the laboratory averaged about 
the same length of time for the last two instars as did individuals 
reared from the egg. Furthermore, the total length of the egg 
stage and developmental and preoviposition periods, as determined 
in the laboratory, equals about one year, which corresponds with 
field observations. In nature the postembryonic developmental 
stages are perhaps somewhat shorter than in the insectary. 
