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Delia platura (Meigen)
Hylemyia platura, Chortophila cilicrura (Rondani)

Insecta, Diptera, Anthomyidae .

Seedcorn maggot, Bean seed fly

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

- Adult: 3 to 6 mm long. The grey to yellowish thorax and abdomen bear a brownish median longitudinal band, the legs are black (*) .
- Egg: pearly white, elongated and about 1 mm long.
- Larva: white maggot which reaches 5 to 8 mm in length at complete development (*) ; the last segment is obliquely truncated.
- Puparium: red-brown, it measures about 5 mm.

Host plants: the bean seed fly maggot is extremely polyphagous (more than 40 host plants): bean, melon, cucumber, spinach, asparagus, tomato, cereals, maize, tobacco, gladiolus, pink (Dianthus), fir (Abies), maple (Acer), etc. It sometimes extends damage caused by other pests; this is the case in radish, turnip, onion, potato.
- Adult: The female deposits several hundred eggs in the ground, generally singly.
The presence of a plant is not necessary, humid soils, rich in organic matter, freshly overturned are very attractive laying grounds.
- Egg: embryonic development lasts a few days.
- Larva: development lasts 3 weeks. It feeds on decomposing animal or plant matter upon which it can fully develop. However, it is also much attracted by germinating seeds and young plants, forming galleries in the cotyledons, the small stems and the young shoots before they emerge from the ground (*) . When the plant is more developed, its tissue is too hard for it to be attacked and the susceptible period does not exceed 3 to 4 weeks. The larvae pupate in the ground at varying depths.

[R]Life Cycle
- 3 to 6 generations can occur during the year according to the regions. The length of the life-cycle varies with temperature (+10°C: 85 days; +20°C: 24-25 days;.
+25°C: 16-17 days).
- The pupae hibernate in the ground and the adults appear as early as the end of winter but mainely in spring. In southern regions, they are present all through the year.

The larvae destroy the shoots of seeds or bulbs in course of development and thinned-out plants. They often cause the plant to rot, leading to the more or less total destruction of seedlings and beds (*) . On asparagus, the attacked spears are deformed, often split, and have a bitter taste (*) .
The damage depends on the size of the larval population, which is governed by the attractiveness of the ground to the adults (freshly overturned soil, rich in recently buried organic matter). In addition, any factors which slow down the speed of germination and the shoot's vigour increases the risk of damage, in particular, low temperatures and excessively deep seedlings.

[R]Common Names
DE: Bohnenfliege, Wurzelfliege, Bohnensaatenfliege, Saatenfliege ES: Mosca de las siembras FR: Mouche des semis IT: Mosca grigia dei semi PT: Mosca cinzenta das plantinhas GB: Bean seed fly, Seedcorn maggot

[R] Images

  1. Delia platura (Meigen) (Coutin R. / OPIE)
    Adult visiting groundsel
  2. Delia platura (Meigen) (Coutin R. / OPIE)
    Damage on seedlings of bean Cotyledons and the terminal bud are destroyed.
  3. Delia platura (Meigen) (Coutin R. / OPIE)
    Damage to seedling of lupin
  4. Delia platura (Meigen) (Coutin R. / OPIE)
    Larva in stem of lupin
  5. Delia platura (Meigen) (Coutin R. / OPIE)
    Damage to seedling of maize Roots and small stems are damaged.
  6. Delia platura (Meigen) (Coutin R. / OPIE)
    Damage on asparagus Attacks cause mottling brown, a twisting of turions and the spears taste bitter.
  7. Delia platura (Meigen) (BASF)
    Damage on seedling of bean

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<I>Delia radicum</I> (L.)
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Delia radicum (L.)
Hylemyia brassicae Bouché, Chortophila brassicae (Wiedemann)

Insecta, Diptera, Anthomyidae .