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Conorhynchus mendicus Gyllenhal
Insecta, Coleoptera, Curculionidae .

Beet weevil

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

- Adult: 12 to 17 mm long, covered with small grey scales which hide the deep black colour of the integument (*) .
- Egg: pale orange colour, 1 mm diameter.
- Larva: whitish, 13 mm long when fully developed (*) .

- This pest attacks sugarbeet. It also lives on Chenopodiaceae.
- Adults: overwinter hidden in the soil of beet fields after harvesting.
- pupa: 15 days for full development.
- Larva: 6 to 7 weeks for full development.
- Eggs: 10 days for development.

[R]Life Cycle
- 1 generation per year.
- Adults: after the imaginal moult, it remains in the soil without feeding; it overwinters and in the spring emerges to feed on young beet plants.
Eggs are laid from May to October, in the soil near the host plant.
- Larvae: these emerge after an embryonic development of 8 to 10 days; at full development, after 40 to 45 days, they pupate in small earthen cells.
The larvae burrow progressively into the soil along the tap root, which they gnaw superficially at first and then more deeply, leaving characteristic signs of their excavations.
On wild Chenopodiaceae, (Atriplex halimus, Beta vulgaris maritima), the species overwinters as older larvae.

- Adults cause severe damage in beet fields by attacking young plants.
In northern regions of Italy, the larvae develop when the tap roots are already well formed and are not very harmful. In the south however, younger roots are available to them which they gnaw at their leisure, causing a lowering in the sugar content of beet and/or rotting of the entire plant.
The larvae dig into the root perpendicular to the axis, thus halting its development.

[R]Common Names
DE: Hohlrüssler ES: Cleonus, Gusano de la remolacha FR: Cléone mendiant IT: Cleono della barbabietola PT: Cleonus GB: Beet weevil

[R] Images

  1. Conorrhynchus mendicus Gyllenhal (Coutin R. / OPIE)
    Adult on root of beet
  2. Conorrhynchus mendicus Gyllenhal (Coutin R. / OPIE)
    Larva in root of beet

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