This notorious worldwide apple pest is often responsible for considerable fruit losses, especially on unsprayed or infrequently sprayed trees. The larvae (apple maggots) burrow singly into the flesh of infested apples, filling the cavity with brownish frass; larvae will also feed on the pips. Infested fruits often have a distinct frass-filled hole in the side, surrounded by a reddish ring; sometimes, however, this hole occurs close to the calyx (eye) and is then less obvious. Attacked fruits ripen prematurely and often drop before harvest. Damage is often particularly serious in years when a noticeable second generation occurs. Pear is also attacked. Codling moth larvae occur later in the year and, therefore, in larger fruits than those of the fruitlet-mining tortrix moth, Pammene rhediella (p. 222) or apple sawfly, Hoplocampa testudinea (p. 250). Also, larvae of both other pests typically eject frass from their galleries.
First-generation adults occur mainly from mid-June to mid-July but, depending on the season, may be found at any time from mid-May or late May to August. The moths fly at dusk and activity is favoured by temperatures in excess of 15°C. Eggs are laid either on the foliage or directly on the fruits. They hatch in approximately 2 weeks and the larvae burrow into the flesh of developing fruits, often entering through the calyx (eye). Larvae occur mainly in July and August, and are fully fed in about a month. They then migrate from the fruit and spin cocoons on the bark of host trees. Most larvae overwinter and pupate in the spring. However, in favourable years, individuals spinning-up by the end of July may pupate and give rise to a partial ;econd-generation of adults. Late-developing and second-generation larvae often complete their development only after apples have been harvested. They will then pupate in apple boxes and in sheds where fruit or such boxes are stored.
Adult 15-22 mm wingspan; forewings mainly blackish-brown, more or less suffused with ash-grey, and with a large, metallic, bronzy-black blotch near the tip; hindwings brown (Fig. 291). Egg 1.3 x 1.0 mm, flat, oval and translucent. Larva up to 20 mm long; body pinkish-white but younger instars whitish; pinacula dark; head and prothoracic plate brown; anal plate pale; anal comb absent. Pupa 8-10 mm long, yellowish-brown to dark brown.
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