Description, Biology, Life Cycle, Damage, Common Names, Images
- Host plants: grasses, legumes, flax.
- Adult: the moth appears in July. It leaves the larval place of development at dusk and takes refuge in the nearest woods, bushes and hedges. The female, mated at dawn, is at first inactive but then deposits its eggs on the bark of the tree it used as a shelter (*) .
- Average fecundity: 100 eggs.
- Larva: 6 instars. The caterpillar emerges from the egg in August and shelters in cracks and crevices in the bark. It then spinss a silken hibernaculum inside which it remains in diapause until March of the next year. When activity resumes (from mid-March to mid-May), the young larva lets itself hang on the end of a silk thread; it is tranported by air currents in various directions and at various distances then lands and begins to feed. In the case of cereals, it penetrates the leaf parenchyma and lives as a miner during its 3 first instars (*) .
Later, it abandons its gallery and reaches the uppermost leaves where it causes a pinching of the lamina. Having reached the fifth stage, it moves towards the top of the stems; it then becomes extremely harmful by attacking the ears (*) .
- Pupa: pupation takes place in the ear sheath.
- 1 generation per year.
Damage is of 3 types:.
- White ears: in this case, the caterpillar has sectioned the stem under the ear above the last node. Such damage is characteristic in June. The cut stem stands above the mass of other curved ears.
- Mutilated ears: the caterpillar has attacked the ear, eaten the contents of several spicules.
- Atrophied grains: the larva has sectioned a part of the stem, disturbing the sap flow; the ear being poorly nourished contains numerous atrophied grains.
Threshold levels of invasion currently accepted are of 1 larva per 10 feet of barley (25 to 30 larvae per m2) and 1.5 larvae per 10 feet of wheat (35 to 40 larvae per m2).
HYPPZ on line : Species (scientific name), Pests (common names), Glossary, Crops.