442 BEITISH LEPIDOPTERA. 



spiracular hairs bent downwards over the edge of the twig, which, added 

 to their mottled coloration, make the larva? very difficult of detection. 

 Those of Eutricha quercifolia are perhaps pre-eminent in this respect. 

 The adaptive protective resemblance of the larva of this species to its 

 resting-place is much increased by the row of fleshy protuberances 

 along the sides of the caterpillar, which enables it to rest on twigs and 

 tree-trunks by day without casting a sharp shadow. Similar lateral 

 developments are seen in the larva? of P. populi, Catocala, &c, and 

 there is no doubt that the lateral drooping hairs of Eutricha quercifolia 

 and Poecilocanqia populi help to produce a more perfect protective result. 

 Packard says that the study of a collection of central African Lasiocampid 

 larva? from the Upper Congo (the group being especially well-developed 

 in the tropics of South America, Africa, and Asia, where they rival in 

 size the colossal Attaci) shows that the armature of their spines is the 

 most formidable of any of the Bombyces (in sensu latiore), and he fur- 

 ther adds that "the most spiny forms appear to be tropical, which tends to 

 prove that originally nearly all our spiny caterpillars appeared in warm 

 regions, whilst the densely hairy forms (e.g., Arctians) predominate in 

 cool, temperate regions." Bacot observes that the Arctiids of the 

 temperate regions tend to have a much more spiny and formidable 

 armature than the Lachneids of the same region. 



The differences in the cocoons made by the Lachneid larva? are very 

 striking. Lachneis lanestris, JPachygastria trifolii, and Lasiocampa querciis, 

 make the close, hard, dense, egg-shaped cocoons from which the name 

 Eggar has been derived, and which closely resemble the very similar 

 cocoons spun by the Cochlidids. These cocoons are coloured with a 

 fluid which is poured out upon the silk from the alimentary canal, and 

 is supposed to be a chlorophyll product, whilst they are hardened by a 

 deposit of oxalate of lime secreted in the malpighian tubules and 

 poured out from the anus upon the silk when it has been woven. 

 Starvation just previous to spinning by not supplying the larva with 

 the requisite chlorophyll stain results in the formation of a pale- 

 coloured, whitish cocoon. Some of the cocoons of L. lanestris are 

 dark-coffee-coloured, and they vary through different grades of intensity 

 to white. Even in nature some of the cocoons of L. querciis are pale 

 brown, others, especially of var. callunae, are frequently almost black, 

 and one is forced to the conclusion that the general darker coloration 

 of the cocoon of the latter is due to the different food-plants, especially 

 if, as has been suggested, the colouring matter is a direct derivative of 

 the chlorophyll in the food, the chlorophyll of some plants being 

 notably darker than that of others, although it would appear also that 

 moisture has considerable effect in darkening some cocoons. The 

 soft, somewhat flimsy cocoons of 21. neustria and 21. castrensis, with 

 their pale yellow or sulphur-coloured particles of aragonite mixed with 

 the silk are very different from those just described, but like them, 

 they often lose their characteristic colour, and become white. This form 

 of cocoon is not unlike that of Cosmotriche potatoria, which is, however, 

 more parchment-like, and this, again, except in colour and texture, is not 

 very dissimilar from that of K. quercifolia, whilst it is very similar to that 

 of Li. ilici folia. The cocoon of 2Lacrothylacia rubi appears to be a very 

 strongly modified form of the Malacosom a cocoon, forming a long tubular 

 structure, sometimes three or four inches long, inside which the pupa 

 moves up and down to take advantage of the sun. As a rule, however, 



