THE REARING OF CATERPILLAKS 81 



been made) of such a width that it will exclude the caterpillars from the 

 compartment below, and at such a height as will allow the vessels 

 which contain the stems of the food plants to pass easily beneath it. 

 One of what are now the sides of the breeding cage can be filled in 

 with a sheet of glass, cut so as to exactly fit the inside of the box, 

 but prevented from falling in, by means of small strips of wood. If 

 the glass is to form the door, it can be kept in place by movable 

 buttons. The other side can be covered with mosquito netting 

 tacked on to the sides of the box, or if the entrance is to be here, on 

 the inside of a frame of the same size as the glass. The inside is 

 chosen so that the netting may touch the false floor, and an extra 

 strip of wood may with advantage be fastened across the frame along 

 the line of the floor to prevent caterpillars from pushing down into 

 the lower half of the enclosure. More elaborate cages, made ex- 

 pressly, can of course be utilised, which, if they are to be used after- 

 wards to contain the adult insects, should be covered with gauze all 

 round. Holes should be bored in the false floor at convenient 

 intervals, and after branches have been pushed through into the 

 water below, the interstices should be plugged with cotton wool to 

 prevent the caterpillars from crawling through them. 



One advantage of using gauze is that, should the butterflies or 

 moths be allowed to emerge in the same cage, as suggested, their 

 wings will not be damaged as they would be if they beat them 

 against glass. 



Tent-making caterpillars like those of the lackey moth (see figure 

 114, Part I) form excellent material for observations. 



It is quite easy also to repeat the experiments made by Professor 

 Poulton to show the power that caterpillars possess of turning into 

 chrysalides of a colour which more or less agrees with the surround- 

 ings in which they have to pass their period of rest, or of modifying 



II F 



