Naval Orange Worm

NAVEL ORANGEWORM
Despite the name, the Navel Orangeworm is a mainly a pest of almonds in California. The adult moths have irregular silver-gray, and black forewings and legs, and a snout-like projection at the front of the head. The larvae do the real damage.

Damage
Almond growers lose millions of dollars to Navel Orangeworms each season. Nuts infested with the Navel Orangeworm are unmarketable because the larvae feed on the nutmeats and produce webbing and frass. Navel orangeworms do not damage sound walnuts until the husks begin to split. Navel Orangeworm larval damage can also lead to fungal infections. Two cultural practices--the effective removal of mummy nuts in fall or winter, and rapid early harvest provide the most effective control. Several parasitic wasps are known to parasitize Navel Orangeworm.

Life Cycle
The female lays eggs that are opaque white when first laid, and after about a day turn pink to reddish orange. Eggs are laid on mummy nuts in the trees, or new crop nuts which have split. They hatch within 4 to 23 days, depending on temperature. New larvae are reddish orange and later vary from milky white to pink in color, and have a pair of crescent shaped marks on the second segment behind the head. After hatching, the tiny caterpillars enter nuts and do not emerge until they are adults. Several larvae may infest one nut and produce substantial webbing. Pupation is during the spring. Pupae are light to dark brown, encased in a woven cocoon, and found inside nuts or between hulls and shells. There are three to four adult flights per year. Navel Orangeworms overwinter as larvae inside mummy nuts on the tree and in trash nuts left on the ground and around hullers. Moths of the overwintered brood start emerging in April, and peak emergence usually occurs from late April to mid-May, depending on season and locality.