142 



NATURE SKETCHES IN TEMPERATE AMERICA 



birds, and the warning colors doubtless function in connection 

 with these spines in thwarting the attacks of birds and lizards. 



The Saddle-Back Lahva 



F all the queer tenants harbored by 

 the witch-hazel, perhaps the most 

 singular one is the saddle-back 

 larva. It is an August visitor, 

 coming about the middle of the 

 month. A somewhat mutilated 

 leaf, with a ragged margin, may 

 give the first hint of the presence 

 of the larva. 



It lives in gregarious colonies when young, and a quainter 

 brood can rarely be found. Fully exposed along the margin 

 and lined up like a company of soldiers, they feed upon the 

 leaf. Gradually this process goes on until only the veins or 

 stems remain. Such a colony as described was found on the 

 witch-hazel. A photographic illustration of this brood shows 

 them in their favorite attitude when eating. They feed on 

 the leaves of many species of trees, including the younger, 

 fresh green underbru.sh of the oak and basswood, and some- 

 times they are found on fruit trees. 



These caterpillars have short bodies and both ends look 

 alike. Each extremity is provided with a pair of dark spiny 

 tubercles. At the head they are somewhat larger and supplied 

 with supplementary tufts of hair. On the back of the larva 

 is a square green patch, while at the middle there is a purplish 

 brown saddle, surrounded by a ring of white, edged with 

 black. 



The larvae are provided with stinging hairs fringing the sides 

 of the body. On coming in contact with the human body 

 where the skin is thin, they often cause a painful sensation, 

 not unlike that of nettle. It is thought that the hairs break 

 off in the skin, thus producing an irritating effect. 



"It is a most suggestive fact," says Wallace, "that in cases 

 where color is required only as a warning, as among the uneatable 

 caterpillars, we jBnd, not one or two glaring tints only, but 



