Page 44 - AG 7-2011 Revised 2016

Naval Orange Worm: PUPA

5 MM

Photo Courtesy of UNIVAR Photo Courtesy of UNIVAR

Naval Orange Worm

Photo Courtesy of UNIVAR Photo Courtesy of UNIVAR

1.Antenna-Small 2 segmented 6.Thorax- NAVAL ORANGE WORM
2.Eyes- ocelli numerous 7.Petiole-none
3.Head-true head capsule 8.Abdomen-8 segments 6 43
4.Legs- thoracic legs 3-proleg 4 9.Color- yellowish color 4 Photo Courtesy of UNIVAR
5.Wings- none on larva 10.Other- larva produces webbing

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.

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.

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