826 BRITISH LEPIDOPTERA. 



in outline ; pale straw-yellow in colour. The eggs are laid in the case, 

 and touch one another, but are separable without breaking ; they have a 

 very small quantity of wool very evenly scattered all over ( ? from 

 Bournemouth). 



Case. — The full-grown case is about 8mm. in length, consists of a 

 silken tube covered with small particles of vegetable debris at its 

 anterior end, and is surrounded, throughout its length, by about 12-16 

 pieces of fine grass of varying lengths, placed parallel to each other, and 

 of these three or four extend beyond the posterior end. There is much 

 difference in the coarseness of the materials used, and that of the 

 females seems to be uniformly coarser than that of the males, whilst the 

 cases of the former are also usually larger. The inside of the case is 

 lined with white silk, but there appears to be no special spinning inside 

 the case when the larva utilises it for a puparium, the caterpillar 

 apparently simply turning round before undergoing pupation (De- 

 scribed June 12th, 1899, from Mecklenburg case). Bruand simply 

 notes the case as being of very weak structure, and covered with small, 

 very thin straws. Barrett says that the case is " rather thinly con- 

 structed of silk, covered with slender bits of dried grass placed 

 longitudinally, some parallel, others rather diverging, so as to give it 

 a rather loose appearance." There is a distinct difference in the size 

 of male and female cases so that one can separate them readily before 

 emergence. Hofmann also notes the female cases as being larger than 

 those of the males, which he describes as being 3"'-4'" generally 

 covered with fine, closely laid grass stalks. 



Comparison of the cases of Fumea casta, Masonia crassiorella 

 and M. affinis. — The case of F. casta differs from that of ill. affinis by 

 its smaller size (3-4 lines), and is usually covered with finer and more 

 closely attached grass-culms, the case of affinis being usually clothed 

 with projecting material that gives it a bristling appearance (Hofmann). 

 Caradja observes that the case of F. casta is readily distinguished from 

 that of M. crassiorella, the pieces of grass standing off much less 

 markedly in those of tho former than in those of the latter species. 



Habits of larva. — The head, pro- and mesothorax are protruded 

 when the larva is active, and as the case gets larger and heavier it is 

 carried less perpendicularly, and hangs down vertically when the larva 

 is crawling up or along any surface that allows the case to fall in this 

 position. When disturbed the head is withdrawn and the anterior end 

 is brought down close to the surface on which the larva is resting, so 

 that the larva is entirely hidden. The larva? as soon as they emerge 

 construct a case from the maternal one, or from the silk covering the 

 eggs and afterwards use outside material. They are carried perfectly 

 vertical when young, and the young larva? move at a very rapid 

 rate. Hamm notes : A case found on a leaf on July 15th, 

 1895, at Mortimer, Berks, produced a batch of larva? on 19th, 

 which fed on knotgrass and made their cases with shreds of 

 paper ; they did well until the autumn when the whole lot died 

 off. On July 4th, 1897, at Bagley Wood, Berks, another case 

 found on a birch leaf gave a brood that hatched on July 18th, these 

 were fed on birch until the beginning of November, when this food- 

 plant failed; the larva? lived on until December and then died. On 

 July 14th, 1898, at Bovey Tracy, Devon, another case was found on a 

 birch leaf which produced larva? on July 18th, these constructed 



