SPAN-WORMS. 203 
foliage or racing up and down the trunks of the tree, trying 
to reach with their front feet the worms suspended by silken 
threads. Evidently the caterpillars realize their danger, be- 
cause if we imitate the motion of one of these beetles with a 
little stick upon a leaf all the worms immediately drop, but 
remain suspended in the air until they imagine all danger is 
past. Insect-eating birds devour large numbers, and Shrews 
and Skunks find and devour the caterpillar above and below 
the ground. Spiders prove also of great help, as do some 
large wasps, such as the Potter-wasps, which store theclay- 
cells made by them with canker-worms, as many as twenty 
being found in a single cell. 
These canker-worms are general feeders but are partial 
to the plum, cherry, linden and elm. The different states of 
this species are shown in Fig. 196. 
THE WINGLESS OPEROPHTERA. 
(Operophtera bruceata Hulst). 
This moth is closely allied to the canker-worms and like 
them possess a wingless female; in Europe it is also almost 
as destructive. It is not common 
and the male can be readily recog- 
nized from the true canker-worms by 
having the ochreous fore-wing more 
rounded and ornamented with many 
Fig. 197.—Operophtera i ‘ : 5 : : 
bruceata Hulst.; male. wavy lines; Leas illustrated in Fig. 
197. The caterpillars feed upon the apple and other plants. 
THE SCALLOP-SHELL GEOMETER. 
(Calocalpe undulata Linn.). 
This is a rather common moth, but always attractive on 
account of its beautiful marking. It has white or vellowish 
