Insecta, Lepidoptera, Tortricidae .
Description, Biology, Life Cycle, Damage, Common Names, Images
- Host plants: the caterpillar can develop on many species of forest tree, but prefers apple or, secondarily, pear, cherry, plum, or apricot and red currant.
- Adult: longevity of 1st generation adult: 1 month. Mean fecundity: 150 eggs.
- Eggs: time until hatching, 90 day-degrees.
- Larva: 4 larval instars; summer larva fully grown after 3 weeks.
- Pupa: developmental duration, 10 to 20 days (end of April or beginning of May).
- 2 generations per year.
- Emergence of the adults corresponds to apple stages I and J (*) . Mating and oviposition occur in the evening, when temperatures are around 13°C.
- The summer caterpillars appear at the end of June and attack the leaves at the tips of the stems, and then the leaves lower down. When the leaves attacked are in contact with fruit, the caterpillar will also graze its upper epidermis (irregular pattern) (*) and occasionally dig roundish holes (3 to 6 mm deep).
- The 2nd-generation adults appear in August-September, mate and lay eggs. The autumn caterpillars eat the leaves and gnaw the fruit. They then seek a hiding-place to overwinter in (L2 to L4). When the summer is hot, growth may continue and give rise to moths which die without reproducing.
- L2 overwinters in a loosely woven cocoon in the crook of a forking twig, bud axil, in a leaf or in a crack in the bark. It becomes active again at the end of winter apple-tree (stage C (*) ), penetrating the buds and, by means of silken thread, attaches the leaf tips and buds together. It eats the small outer leaves and floral parts, sometimes attacking a number of blossom trusses. Some larvae hang down on3 the end of silken threads, and may then be dispersed by the wind, occasionally over long distances.
The damage to the leaves does not harm the tree's growth (*) . On the other hand, the damage to the fruit can be extensive and costly. The fruit attacked heals poorly and the lesions allow fungi to invade. All varieties may be attacked, the most susceptible of apple being Rennets, Canadian pippins, Golden Delicious, Red Delicious and its mutants, and among pear: Williams, Beurré Hardy, Doyenné du comice pear and Passe-crassane.
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