VI HETEROCERA — LYMANTRIIDAE 407 



together with others much longer and softer, these being some- 

 times also amalgamated to form pencils ; the coloration of these 

 larvae is in many cases very conspicuous, the tufts and pencils 

 being of vivid and strongly contrasted colours. Some of these 

 hairy larvae are poisonous. A cocoon, in which much hair is 

 mixed, is formed. The pupae are remarkable, inasmuch as they 

 too are frequently hairy, a very unusual condition in Lepidoptera. 

 The Lymantriidae is one of the largest families of the old group 

 Bombyces; it includes some 180 genera and 800 species, and is 

 largely represented in Australia. Dasycliira rossii is found in the 

 Arctic regions. In Britain we have eight genera represented by 

 eleven species ; the Gold-tails, Brown-tails and Vapourer-moths 

 being our commonest Bombyces, and the latter being specially fond 

 of the London squares and gardens, where its beautiful larva may 

 be observed on the leaves of roses. Most of the Lymantriidae are 

 nocturnal, but the male Vapourer-moth ilies in the daytime. In 

 this family there are various species whose females have the 

 wings small and unfit for flight, the Insects being very sluggish, 

 and their bodies very heavy. This is the state of the female of 

 the Vapourer-moth. The males in these cases are generally re- 

 markably active, and very rapid on the wing. 



Some of these moths increase in numbers to an enormous 

 extent, and commit great ravages. Psilura monacha — the Nun, 

 " die Nonne " of the Germans,^ — is one of the principal troubles of 

 the conservators of forests in Germany, and great sums of money 

 are expended in combating it ; all sorts of means for repressing 

 it, including its infection lay fungi, have been tried in vain. The 

 caterpillars are, however, very subject to a fungoid disease, com- 

 municated by natural means. It is believed, too, that its con- 

 tinuance in any locality is checked after a time by a change 

 in the ratio of the two sexes. It is not a prolific moth, for it 

 lays only about 100 eggs, but it has been shown that after 

 making allowance for the numerous individuals destroyed by 

 various enemies, the produce of one moth amounts in five genera- 

 tions to between four and five million individuals. The larva 

 feeds on Coniferae, and on many leafy trees and shrubs. The young 



' This moth is known under several generic names — Psilura, Lijiaris, Ocneria, 



Lymantria ; there is now a very extensive literature connected with it. A good 



general account by Wachtl may be found in Wien. ent. Zeit. x. 1891, pp. 149-180, 

 2 Plates. 



