Description, Biology, Life Cycle, Damage, Common Names, Images
This species is widely distributed is the northern hemisphere and develops on wheat, rye and barley.
- Duration of pupation: about 2 weeks.
- Number of eggs produced: 30-40 per female.
- Young larvae hatch about 5-10 days after egg-laying. The feeding period lasts about 3-4 weeks.
- There is 1 generation per year.
Larvae overwinter in a subterranean, round and transparent cocoon, moving directly to the upper layer of the soil to pupate when temperatures rise in the spring.
- Living for only a few days, the midges start flying at approximately the flowering period of wheat (*) . They usually remain in the soil and, after sunset, especially during still nights, fly to the ears to lay their eggs. If the air is humid enough, egg-laying may take place during the day.
- Duration of the flight period: 2-3 weeks, sometimes longer.
- Number of eggs produced per female: 30-40. Eggs are laid singly on ears at the pre-flowering stage. If eggs are laid later, larvae are incapable of developing normally.
Young larvae hatch about 5-10 days after egg-laying and feed for 3-4 weeks.
Once they have reached their final size, larvae leave the ears when the air is humid and enter the upper layers of the soil, spinning a cocoon in which they will remain in a state of diapause for an extended period..
- Larvae usually pupate the following spring but may remain in a state of diapause for several years. In a population, 0-96% of individuals enter a state of diapause, depending on factors such as rainfall, soil humidity and rotation of crops.
Mainly parasites, diapause and phenological factors determine the life of this species. Heavy rainfall during the flight period can cause individuals to fall to the ground and die.
Average infestation on wheat of 15 larvae per ear can lead to yield reductions.
Early infestations hinder the formation of seeds (*) while late infestations cause them to become brittle. Partial attacks distort ears, which become soft to the touch and seem abnormally thin. Ears of rye may exhibit mines.
The envelope of the grain often ruptures and a secondary fungal infection develops. Grain value, the germination power, the speed of germination, the vigour and the weight of grains can be considerably reduced. The baking quality of rye is poor.
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