Life-history. The egg is oval, cylindrical in section, and measures about 0.5 mm. in length. It appears smooth, though the outer surface is actually reticulate; the colour is an indefinite bluish-green, becoming yellow before hatching. Eggs are laid in spots determined by the ability of the moth to assume a position of rest; they never rest on the upper surface of a horizontal leaf but can rest on the lower surface of a leaf or place at any angle from the perpendicular to the horizontal; they appear always to hang from an object rather than rest on it; on the broad leaves of cucurbitaceous plants, eggs are laid on the lower surface; on the alternative foodplant, pigeon-pea, they are laid on the flower-buds and young pods. Eggs are usually laid singly, often only one on a pod or flower-bud, several on a young leaf. In the Insectary, 193 eggs were laid by two moths, all being laid at night. The eggs hatch in two days in warm weather up to six days in the colder weather of the North Indian winter:—
| Eggs laid | Eggs hatched | Duration |
|---|---|---|
| 7th September | 9th September | 2 days. |
| 8th " | 11th " | 3 " |
| 9th " | 12th " | 3 " |
| 16th " | 19th " | 3 " |
| 9th February | 15th February | 6 " |
The larva emerges from the egg by biting away a small portion and then pushing through. The empty egg-shell is not eaten. On hatching the larva is about a millimetre long; the head is dark brown and shiny; there is a distinct prothoracic shield; the segments are well marked and on each segment there are five tubercles bearing from one to three hairs each; these tubercles are regularly arranged and form rows along the body; the round spiracle lies between the second and third tubercles. There are three pairs of thoracic legs and five pairs of prolegs.
The larva is of a yellowish-green colour on hatching, becoming green as it grows older and remaining of that colour; on the pods of pigeon-pea, which are coloured usually in green with brown stripes, the larva also has a lateral brown stripe and assimilates very closely to the colour of the pod; on green leaves of pumpkin, etc., it is green and this assimilates it to the pure green of the leaf. The larva alters little in appearance, during the various instars; in the last instar the dorsal three black tubercles are developed into more prominent protuberances; the first and third are yellow, the second black, each with
