BROWN-TAIL, SMALL ERMINE, AND SPURGE MOTHS. 311 



surrounded by the nest, or whether they had been cut from the 

 boughs outside, and carried into the interior by the inhabitants. 

 The latter supposition is implied, but it can hardly be a correct 

 one, as it is directly contrary to our present knowledge of the 

 habits of caterpillars. I believe that no lepidopterous larva is 

 known to fetch food from a distance, and to store it for future 

 consumption. As far as we know at present, the caterpillar has 

 not the least thought for the morrow, but simply devours the 

 leaves where they grow. 



There are many species, such as the larva of the common 

 Brown-tail Moth (Porthesia auriflua), or of the Small Ermine 

 Moth ( Yponomeuta padella), which travel by day to considerable 

 distances in their search after food, and return at night to their 

 common habitation, guided by the threads which they continual- 

 ly spin as they crawl along. But no caterpillar is known which 

 is gifted with the instinct of cutting off leaves and bringing them 

 home for food, and we may therefore infer that the leaves in ques- 

 tion were growing on the branches, and that the nests had been 

 purposely spun round them. 



There are, however, one or two species of British insects, be- 

 longing to the lepidoptera, which do cut off leaves and use them 

 for the construction of the cocoon, though they do not employ 

 them for food. These insects are moths, belonging to the genus 

 Acronycta, and popularly called Spurge Moths, on account of 

 the plant on which they reside. One of these species makes a re- 

 ally curious pensile cocoon from the leaves of the cypress spurge 

 (Euphorbia cyjiarissias), rather a scarce perennial plant about a 

 foot in height, growing about woods and the borders of the fields. 

 The leaves of the stem are lance-shaped, and those of the branch- 

 es almost linear, like grass blades, and it is of these latter that the 

 insect makes its habitation. 



About October, the caterpillar begins to make its house, and 

 does so in a very curious manner. Detaching a leaf from a 

 branch, it fastens one end to the stem, and then bends the leaf so 

 as to form a loop, and fastens the other end in a similar manner. 

 A number of the leaves are placed nearly parallel to each other, 

 so that when they are firmly woven together they form a bag-like 

 cocoon, fixed to the stem of the plant by one side, and being up- 

 right like that of the burnet moth. Its texture is, however, very 

 unlike that of the burnet, being loose, almost wholly composed of 

 vegetable matter, and comparatively flimsy. 



