These portions of an entomologist's work certainly take up a great deal of his time, and also require much patience and perseverance; but the advantages derived cannot be over-estimated, for in addition to the knowledge gained of the early stages of insect life, this kind of work will enable him to place in his cabinet a number of gems he would otherwise have not and probably know not. Occasionally a prize may be obtained in the form of a cluster of eggs (ova) of a rare species, in many instances the larvæ are to be obtained with comparative ease, while the perfect insects of the same species are not often seen or not easily captured, and many a
rare pupa has been dug out of its hiding place during a season when the entomologist had but little other work to occupy his time.
These and other similar subjects we shall now consider in turn.
Collecting Ova
The collection of ova may be carried on more or less throughout the year. A number of moths are out in February, and even in January if the weather is mild. These soon lay their eggs, which are hatched about the time that the buds of the food plant are breaking. From this time till late in the summer the ova of various species are being deposited, the average period from laying to hatching being from two to three weeks. Then, during the autumn, when the leaves of food plants are turning brown and crisp, ova are still being laid, but these remain unchanged till the new buds of the following spring are bursting.
Of course if you intend searching for the ova of particular species you must previously ascertain the favourite haunts of those species, become acquainted with their food plants, and also with the season or seasons during which the eggs are laid. But the few following hints will suffice as general instructions for the search.
In nearly all cases we must expect to find ova on the food plants of the respective species, but at times, especially with certain moths, we may come across them in the most unlikely spots. Thus, it sometimes happens that a moth settles on a street lamp, and lays her eggs on the framework round the glass, or even on the glass itself. The same thing may take place on the sash or glass of a brightly lighted window.
Such occurrences, however, we must regard as accidental and comparatively rare, and therefore we confine our searchings for ova to the food plants of the species we require.
As a rule the under sides of the leaves will yield the most, but we have already noticed ([page 18]) that some moths leave their eggs exposed on the upper surface. Again, some larvæ feed on flowers and seeds and fruit, and the eggs of such are deposited on these parts. Those insects which feed on the leaves of shrubs and trees often lay their eggs on trunks, branches and twigs. Sometimes these are laid singly, sometimes in dense clusters; and it is not unusual to find them arranged in rings or spirals with great regularity. When examining the trunks of trees for ova it is necessary to look well into the crevices of the bark, for some insects take
particular care to lay them in deep sheltered chinks; but others take no such precautions, and deposit them on exposed ridges or plain surfaces where they are easily discovered.