The insect pest inside the mangoes is the mango nut weevil or stone weevil, Sternochetus Mangiferae. The young one or grubs as soon as they hatch out from the eggs tunnel in a zig zag manner through the pulp, endocarp and the seed coat and finally reach the cotyledons.
As the fruit develops, the tunnel gets closed . The grub feeds on the cotyledons and destroys them. The adult emerges from the pupae also and feeds on the developing seed and this may hasten the maturity of infested fruits.The adults hibernate in between the crevices on the tree trunks. The weevil attacks only mangoes.
The dark brownish stout weevil measures about 6mm long. The female scoops out the surface of the developing fruit and deposits the eggs singly. On a fruit 12 to 36 eggs may be deposited. The fluid that oozes from the fruit covers the eggs. The incubation period is 7 days.
The grub is apodous, fleshy, light yellw with a dark head and pupates inside the nut itself. It emerges as an adult in 7 days. The total life cycle from eggs to adult is 50 days.
Source : The Hindu