266 NATURAL HISTORY. fcH. XVI 



CHAPTER XVI. 



SOCIAL CATERPILLARS. 



Move in regular Files Form Nests lined with Silk " The Procession- 

 ary"The Leaf -rolling The Leaf-bending TJie Leaf -mining C a 

 terpil.lar. 



THE caterpillars described in the last chapter are 

 hermits, which lead a solitary life : there are, how- 

 ever, other tribes which spend either a part or the 

 whole of their vermicular life in society. The per- 

 fect insect deposites all its eggs on the same leaf or 

 plant, and the caterpillars proceeding from these 

 eggs are disclosed about the same time, and fre- 

 quently live together until they assume a different 

 form. The gold-tailed moth (Jlrctia Chrysorrhcea) 

 is one of those insects which lay eggs productive of 

 social caterpillars. They deposite their eggs in a 

 cover, formed of hair plucked from their own body. 

 The moment one of these caterpillars is evolved, it 

 seeks its food on the leaf on which the Author of 

 nature had taught the parent insect to deposite it : 

 a second soon joins the first-born : and a third speed- 

 ily follows the second : thus a row of caterpillars 

 parallel to each other may be seen reaching nearly 

 across the leaf: a second row then begins to form 

 itself; which, when it has extended across the leaf, 

 is succeeded by a third. The whole of the upper 

 surface of the leaf becomes thus entirely covered, 

 except a small space left open for the first rank to 

 feed upon. The heads of each rank being generally 

 in the same line, they all advance simultaneously ; 

 and their progress has very much the appearance of 

 a regular military movement ; as may be seen by the 

 annexed figure. 



