Insecta, Diptera, Anthomyidae .
Description, Biology, Life Cycle, Damage, Common Names, Images
- Host plants: onion, shallot, leek.
- Adult: lifespan does not exceed 2 months. Fecundity: 150 to 200 eggs.
- Egg: laid singly or in clusters of 15 to 20 in the vicinity of the host plant, often on the neck, sometimes at the leaf's axil or between the scales of the bulb. Embryonic development lasts 2 to 7 days.
- Larva: the lifespan depends on the temperature, 45 days at 15°C and 17 days at 25-30°C. The larva penetrates the tissue between the leaf shoots or at the base of the roots (*) . At the site of damage, bacterial mould settles particularly caused by Bacillus carotovorus. The larva feeds on these decomposing tissues. At the end of its development, it leaves the host plant and buries itself in the ground at a depth of 5-10 cm to pupate, or it enters diapause at the beginning of September when the ground temperature is below 15°C.
- Pupa: development lasts between 15 and 25 days.
- From 2 to 5 overlapping generations depending on the regions.
- The adult, emerging from overwintered pupae, appears in April in the Mediterranean region and towards the end of May further north. The female lays in successive cycles at intervals of 15 days. Between the egg laying periods, the female does not remain in the crops. The second-generation adults emerge in July and lay in the same way as the spring adults.
- The most serious damage is caused by the first generation which extends over a very long period owing to the female longevity. It occurs especially on seedlings of onion and leek, on thinned out onions and on shallots.
- On young onion seedlings, the damage is very serious: the plant wilts and dies (*) . A larva can attack several seedlings in succession. If the plant is more developed, it wilts, especially in warm weather and can die. Later, the fly promotes the onset of rot, visible only at the time of uprooting, which attracts other saprophitic Diptera whose maggots are then found in the bulb.
- On thinned-out leeks, the fly's attacks can be detected through a yellowing of certain zones and a wilting of the plants which rot.
In France, 4 or 5 overlapping generations in the South-West, 2 to the north of the Loire.
DE: Zwiebelfliege ES: Mosca de la cebolla FR: Mouche de l'oignon IT: Mosca della cipolla PT: Mosca da cebola GB: Onion fly
HYPPZ on line : Species (scientific name), Pests (common names), Glossary, Crops.