66 NATURAL HISTORY. [cH. III. 



assumes a smooth appearance. Reaumur observed 

 that it repeatedly pushed its head with considerable 

 force against the inner surface of the cocoon, so as 

 to force the more moistened earth to run through 

 the meehes of its net. Hence it is evident that the 

 silken net has both an external and an internal cov- 

 ering of mud. When the operation was completed, 

 Reaumur opened the cocoon and took it away from 

 the caterpillar, which, however, made a second du- 

 ring the night ; it was, however, but slightly cased 

 with mud, the insect not having sufficient fluid left 

 to moisten the grains of earth with. The moths 

 produced from some of the cocoons thus construct- 

 ed, were "found dead in the breeding-cages at the 

 end of October. They were of an ashy gray col- 

 our, with two palish bands across the wings, and 

 are considered by Ernst as the oak eggar moth 

 {Trichocera cratagi). The cocoon which we have 

 figured from Reaun^ur is similarly formed, but the 

 caterpillar differed in its markings from those of the 

 former caterpillars, and Reaumur did not succeed in 

 rearing it to the perfect state. 



The caterpillars of numerous other species of 

 moths form their cocoons of chips of wood and bark, 

 connected together with silk ; but these are gener- 

 ally constructed without much regularity in the ar- 

 rangement of the chips. Among these, that of the 

 puss moth, subsequently noticed, is one of the hard- 

 est cocoons with which we are acquainted. It is 

 composed of very minute gnawed bits of bark, 

 strongly cemented together with a gummy secretion 

 mixed with silk. There is, however, another spe- 

 cies, whose proceedings have been detailed by Reau- 

 mur, which far exceeds the others in the neatness 

 and ingenuity of its case ; and it is consequently to 

 be regretted that this author has not recorded the 

 particular species, nor figured the moth produced 

 from it. Messrs. Kirby and Spence, however, sup- 

 pose that it may probably be the smallest black arch 



