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Delia antiqua (Meigen)
Phorbia antiqua, Hylemyia antiqua

Insecta, Diptera, Anthomyidae .

Onion Fly

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

- Adult: 6 to 7 mm long, yellowish grey with 5 dark stripes on the thorax, yellowish wings, black legs and antennae (*) . Adult looks like a large domestic fly, Musca domestica L. (Dipterae, Muscidae).
- Egg: dull white, elongated and longitudinally striped, it measures 1.5 mm in length.
- Larva: a white maggot which reaches 8 mm when its development is complete (*) . The precise identification of this larva can be achieved only in a laboratory by examining the mouthparts and the anal segment.
- puparium: light brown to dark brown, ringed and ovoid, it measures 7 mm in length and 2.5 mm in diameter.

- 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 15C and 17 days at 25-30C. 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 15C.
- Pupa: development lasts between 15 and 25 days.

[R]Life Cycle
- 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.

[R]Common Names
DE: Zwiebelfliege ES: Mosca de la cebolla FR: Mouche de l'oignon IT: Mosca della cipolla PT: Mosca da cebola GB: Onion fly

[R] Images

  1. Delia antiqua (Meigen) (Coutin R. / OPIE)
    Female adult on stem of onion
  2. Delia antiqua (Meigen) (Coutin R. / OPIE)
    Damage to onion Leaves wither and become dry.
  3. Delia antiqua (Meigen) (Coutin R. / OPIE)
    Larvae inside onion Onion sectioned to show the larvae (arrowed).
  4. Delia antiqua (Meigen) (Coutin R. / OPIE)
    Larva It caused the onion bulb to decay completely.
  5. Delia antiqua (Meigen) (BASF)
    Eggs deposited on the stipe of an onion
  6. Delia antiqua (Meigen) (BASF)
    Larvae in an onion
  7. Delia antiqua (Meigen) (BASF)
    Damage to onion crop

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HYPPZ on line : Species (scientific name), Pests (common names), Glossary, Crops.

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