Chip boxes are, as a rule, very good and very convenient receptacles for ova. After placing the eggs in these, cover them over with very fine muslin, held in place by elastic bands; and label each as far as you can with the name of the species contained, and other particulars worth remembering. The boxes may then be put in front of a window facing north, or in any situation within or out of doors where rain and sun cannot reach them. A greenhouse is an admirable place in which to keep them, the natural dampness of the atmosphere being apparently a considerable assistance to the tiny larvae just as they are striving to escape from their shell. Whatever place is selected, it is absolutely necessary that the ova be carefully watched, so that each brood may be supplied with the required food plant within a few hours of quitting the shells. When ova are kept in a warm room, very great inconvenience and even loss is sometimes caused by the appearance of larvae before the necessary food plant shows its buds. Yet, on the other hand, it is sometimes a great gain to the entomologist to get certain broods off early in the season, providing the food is at hand; for in this way he can not only get some of his work over during a slack season, but also, if he desires it, secure an additional brood; that is, one brood more than the usual number. Thus, supposing a certain species he is rearing is naturally double-brooded, he can, by judicious management, secure three successive broods before the food plant casts its last leaves. This hastening of the natural events of insect life is known as _forcing_, and merely consists in subjecting the species concerned to a reasonable amount of artificial heat, such as that of a room in which a fire is always kept, or of a hothouse. It is interesting at all times to note the dates on which eggs are laid or collected, and the times at which the young larvae appear. In addition to this all changes that take place in the colours or forms of eggs should be carefully observed; for such changes will assist you in distinguishing between fertile and sterile ova, and also enable you to judge approximately as to the date of the appearance of future broods. _Rearing Larvae_ The main point in connection with the rearing of larvae is certainly the selection and construction of the cages or their substitutes. For newly hatched and all very small caterpillars a small bottle with a wide mouth makes a very fair abode. Put a layer of sand or sifted soil in the bottom, fix in this a small twig of the food plant or lay a few leaves on the top, and then, after the larvae have been introduced, cover the top with a piece of muslin, held in place by an elastic band.