212 ROMANCE OF THE INSECT WORLD CHAP. 



position for any lengthened period. Unaided, the 

 caterpillar does not make the attempt. Fatigue is 

 obviated by spinning a thread of silk, which is fastened 

 at one end to the stem, the other end remains attached 

 to the head of the insect (see Fig. 36). That there is con- 

 siderable tension upon the brace may be seen by cutting 

 it, when the larva falls back with a sudden jerk. In 

 some cases the caterpillar is enabled to endure the 

 strain by holding a leaf or twig with one of its pairs of 

 articulated* legs. 



Many points of detail concur to promote this de- 

 ception of Geometrae. The head is modified from its 

 normal shape into one extremely suggestive of the 

 top of a twig, or some vegetable growth, or at least to 

 convey no hint of its real caterpillar nature. Com- 

 monly it is notched, a plan forming a very natural 

 end to the apparent twig. In the caterpillar of the 

 Small Emerald Moth the segment behind the head is 

 humped as well, while the latter is retracted, so that 

 four blunt projections are produced, carrying out yet 

 more admirably the resemblance to a twig. Similar 

 unevennesses are obtained by the head and first body- 

 rings being bent backwards (see Fig. 36). It might 

 be supposed that the claspers by which the 

 stem is held would excite attention and betray 

 the insects. They however partially surround the 

 branch, and appear to grow out of it (see Figs. 37 

 and 38). Lest the intervening space between the 

 front and hind pairs should reveal the fraud, the 

 underside of the larva is somewhat flattened, so that 

 it lies in contact with a small portion of the round 

 stem, On either hand the furrow is decreased, in 



