200 THE ENTOMOLOGIST. 



approximating their colour to that of their surroundings. Larvae 

 of Catocala nupta found wild on bark were dark, but others kept 

 in flannel became light ; larvse of Biston hii'taria kept in earthen- 

 ware pans were red- brown, while those found on lime leaves were 

 green. A green one turned red-brown in process of preservation 

 as soon as heated (H. M. Golding-Bird, Entom. xi. 109). It has 

 even been stated that certain larv£e are able to change their 

 colour in the course of a few moments, but I have not found any 

 satisfactory evidence that this is the case. It would appear, 

 rather, that the acquisition of a colour like that of the 

 surroundings is a gradual process, and quite involuntary on the 

 part of the larva. In Buckler's admirable work on the larvae of 

 butterflies, a very interesting case is recorded in which larvae of 

 Vcmessa cardui found on Malva developed hairs. In the United 

 States the larvae of this butterfly are said sometimes to occur on 

 sunflower and hollyhock, but I have not heard whether these difi'er 

 in any way from the thistle-feeding form. V. cardui larvae found 

 here (Wet Mountain Valley, Colorado, 8000 feet alt.) on Cnicus 

 ocJiroceutrus, Gray, do not difl'er markedly from the usual form ; 

 but I have only found them on the thistles. 



(3.) Seasonal variation. — Such variation as there may be of a 

 seasonal character exhibited by larvae is probably more due to the 

 nature of the food-plant than to the direct influence of tempera- 

 ture, &c., upon the larvae. Mr. W. H. Edwards (Can. Ent., 1878, 

 p. 5) remarks that the summer larvae of Lyccena psciidargiolus, 

 feeding on Cimicifuga, are white, and of the colour of their food; 

 whereas in the autumn, feeding on a yellow flower, they are dusky 

 and green. Lepidopterists in England are very familiar with the 

 varieties of the larva of Smerinthus popidi, which are more or less 

 spotted with red, and there can be no doubt that these occur more 

 abundantly at certain times and places than at others, although 

 the laws governing these occurrences seem to be unknown. 

 S. myops, an American species, presents a similar variation in its 

 larva ; and according to G. W. Peck (Can. Ent., 1876, p. 339), the 

 larvae showing red blotches are more prevalent in the late brood. 



(3.) Sexual variation. — Secondary sexual characters in larvae 

 seem to be unknown, as might be expected. The larvae of 

 Thyreiis abbotii vary from dirty yellowish to reddish brown, and 

 those larvae with uniform brown mottling were supposed to be 

 females. But C. P. Whitney (Can. Ent., 1876, p. 76) bred some 

 males from the supposed male larvae, and the idea of colour 

 indicating sex in this instance has now been given up. When 

 larvae have insufiicient food they are smaller than usual, and it is 

 said that such larvae produce a preponderance of males, but this 

 is of course the direct result of environment. In Attacus the 

 sexes can sometimes be distinguished in the larval state by a dark 

 blotch on the under side of the last segiueni that bears stigmata. 



