Insecta, Lepidoptera, Plutellidae .
Description, Biology, Life Cycle, Damage, Common Names, Images
- The caterpillar feeds mainly on apple, plum and hawthorn (Crataegus); it can also attack almond.
- Adult: active at dusk (flight, mating, laying).
- Egg: embryonic development lasts 12 to 15 days.
- Larva: after hatching, the young caterpillars enter diapause and remain clustered inside the egg-raft in which they will overwinter. The next spring, the caterpillars leave the egg-raft and penetrate leaflets which they mine and whose limb assumes a reddish brown swollen appearence: the larvae are visible through the transparent epidermis, all orientated in the same direction in a fan-shaped arrangement within the commonal mine ("mining" phase).
After flowering, the caterpillars which have reached the second larval instar abandon the mine and spin silken webs over the tips of the branches whose foliage they eat ("spinning" and "grazing" stages) (*) . Depending on the food requirments, several successive webs are built, up to pupation which occurs in a collective web.
- Pupa: development lasts 2 weeks.
- 1 generation per year.
- The young caterpillars leave the egg-raft and resume activity at mid-April (stage C3 to E2 of apple).
- The flights occur in orchards from July to the end of August.
- The apple small ermine moth causes more or less serious defoliation at the tips of branches of apple trees whose leaves, superficially gnawed assume a reddish colour (*) . The young fruit included within the webs show traces of bites. When defoliation is severe, the summer growth of the fruit is stopped and the latter fall prematurely.
- The importance of the damage varies considerably from year to year. Infestations are frequently spaced out by several years and are witnessed particularly in older orchards.
HYPPZ on line : Species (scientific name), Pests (common names), Glossary, Crops.