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Yponomeuta malinellus (Zeller)
Hyponomeuta malinellus, Yponomeuta padella (L.)

Insecta, Lepidoptera, Plutellidae .

Apple small ermine moth

Description, Biology, Life Cycle, Damage, Common Names, Images


[R]Description
- Adult: 16 to 20 mm wingspan, generally pure white. The fore wings are speckled with black dots and the hind wings are greyish and fringed (*) .
- Eggs: in clusters of 20 to 95, they are disposed in convex, oval or elongated egg-rafts, measuring from 4 to 10 mm. These egg-plates, yellowish after having been laid, brown afterwards, are frequently deposited on the bark of 2-year-old boughs and lean against the axil of buds or the articulation of twigs (*) .
- Larva: straw yellow at the first larval instar, the colour then varies during each interval between two moults: grey-blue slate coloured immediately after moult, then lightening progressively to yellowish grey before the next moult. Each segment bears 2 black spots. The head is black. At the end of its development, the caterpillar reaches a length of 18 to 20 mm.
- Pupal cocoon: the pupa is enclosed in a small silky white cocoon. These are arranged parallel to each other at the centre of a collective web or "pupal nest" (*) .

[R]Biology
- 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.

[R]Life Cycle
- 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.

[R]Damage
- 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.


[R]Common Names
DE: Apfelbaumgespinstmotte ES: Ara˝uelo del manzano FR: Hyponomeute du pommier IT: Tignola del melo PT: Hiponomeuta da macieira GB: Apple small ermine moth

[R] Images

  1. Yponomeuta malinellus (Zeller) Pupal cocoons These cocoons were formed in the last webs sheltering the larvae, on apple leaves.
  2. Yponomeuta malinellus (Zeller) Moth on apple leaf (Coutin R. / OPIE)
  3. Yponomeuta malinellus (Zeller) Egg laying On an apple twig. The eggs deposited as an egg raft are covered with a shiny secretion which renders them almost invisible.
  4. Yponomeuta malinellus (Zeller) Larvae They live grouped together in a network of silken threads and consume neighbouring leaves.
  5. Yponomeuta malinellus (Zeller) Damage on apple Silken webs abandoned after consumption of the foliage.

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