Lepidoptera Facts Rearing Lepidoptera Management Of Ova
In the management of insects in all stages the strictest attention must always be paid to one general rule on which the success of the work almost entirely depends; and that is-keep every specimen as far as possible under the same conditions as those in which you find it in nature.
Applying this principle to ova, we store them in airy and light places, protected from the direct rays of the sun, and avoid handling and rough treatment of any kind. It is also advisable in most cases to maintain a slight amount of dampness corresponding with that of the open air at the particular season of the year.
They do not require much space, and it is certainly desirable not to give much, otherwise the newly hatched larva, when their time arrives, will actively wander all round their premises in search of food, and give you no end of trouble in gathering them up.
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 larva 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 larva 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 larva 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.