SPAN-WORMS. 175 
the form ofa triangle. On the top of segment eight there is 
a projection, sometimes of a reddercolor than the body. The 
under side is light colored, sometimes tinged with red, 
marked with a row of black spots, one to each segment. 
The head, bilobed at top, is: reddish or grayish-ash, fre- 
quently bordered on the top and sides with black. When 
full grown the caterpillars measure one and a quarter inches 
in length; it now forms a cocoon among dead leaves. 
The two anterior pairs of abdominal legs are much 
smaller in the caterpillar of this genus of moths than the 
two posterior pairs, hence they possess a looping gait. 
There are other species of Catacola, the caterpillars of 
which occur upon the foliage of fruit trees, but as the life- 
histories of all are very similar it is not necessary to men- 
tion them. At all events they do not occur in sufficient num- 
bers to cause much injury. A much larger species found on 
apple is C. paleogama Gu., on Plate XXIV, Fig. 177. 
FAMILY GEOMETRIDAE OR SPAN-WORMS, LOOPERS OR MEAS— 
URING-WORMS. 
There is not much difficulty in recognizing these insects. 
The moths possess slender bodies, small heads, and very 
broad, frail and thin wings. The hind-wings are usually 
as much ornamented as the fore-wings, so that the lines of © 
the one pair are often continued across the other. The 
lower-wings are not hidden at rest, but all four wings are 
fully extended in most cases, although exceptions occur. 
The caterpillars lack all save one or at most two pairs of 
false or abdominal unjointed legs, and in moving they first 
extend the body to its full length, then bring the posterior 
end of it close to the front legs, looping the body in the 
center, then stretch out again and repeat the action. This 
peculiar motion has given them the names of Span-worms 
or Measuring-worms, as well as their scientific name Geo- 
