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Delia coarctata (Fallen)
Hylemyia coarctata, Leptohylemyia coarctata, Phorbia coarctata

Insecta, Diptera, Anthomyidae .

Wheat bulb fly

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

- Adult: 6 or 7 mm with a light grey body. The female's legs are yellow with the exception of the blackish tarsi; the male's are blackish.
- Egg: white, oblong, 1 mm long and the chorion with a longitudinal reticulation.
- Larva: pearl white in the first instar, the maggot then becomes creamy. Its size varies from 1 mm at the first instar to 8 mm at the end of development (*) .
- Puparium: light brownish yellow, about 6 mm long.

- Host plants: wheat, barley, rye and various grasses.
- Egg: deposited in open ground, preferably in crumbly soil with a fine texture: fallow, crop harvested early (rape, early potatoes, pea, etc...); the eggs can also be found in ground previously used for maize or sunflower.
- Larva: it undergoes a diapause which is broken only after a period of cold of 4 to 6 months at a temperature below 12°C. A cold winter favours attacks since the cold, acting on the diapause, allows mass hatching, once temperatures rise. Once it has emerged, the larva moves towards the grass seedling. It penetrates the stems where it mines at the level of the terminal bud. During its growth, it can attack successively, 5 to 6 tillers and destroy them. Its development lasts from 6 to 8 weeks then it abandons the plant and pupates in the ground.

[R]Life Cycle
- 1 generation per year.
- The larvae having emerged in February or March following the rise in temperature continue their development at the expense of plants until mid-April when they pupate.
- The adults appear at the end of May and live until September. During autumn ploughing, the eggs are buried in the soil.

The young infested plants first show some wilting then in particular a yellowing of the central shoot which detaches itself easily when pulled (*) . Inside, the stem is mined up to the tillering plate. In late sowings, when the attacks preceed tillering, the damage can be spectacular. When spring is cold, the larval development occurs not only in March and April but also in May. Spring wheat or barley sown to replace a winter cereal can also be attacked.

In France, the most important damage is noticed in the northern half of the country.

[R]Common Names
DE: Brachfliege ES: Mosca gris de los cereales FR: Mouche grise des céréales IT: Mosca grigia del frumento PT: Mosca cinzenta dos cereais GB: Wheat bulb fly

[R] Images

  1. Delia coarctata (Fallén) (ITCF)
    Larvae in stem of wheat
  2. Delia coarctata (Fallén) (BASF)
    Female on ear of wheat
  3. Delia coarctata (Fallén) (BASF)
  4. Delia coarctata (Fallén) (BASF)
    Larva on stipe of wheat
  5. Delia coarctata (Fallén) (BASF)
    Attack on wheat seedlings
  6. Delia coarctata (Fallén) (BASF)
    Puparium in a shoot of wheat

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