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Olive fruit midge

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

[R]Biology
- Species limited to olive.
- Adults appear late June, early July. Fertilized females lay their eggs in olives already attacked by the olive fly (Bactrocera oleae), taking advantage of the oviposition hole of the latter.
Only one egg is usually laid, but sometimes more.
- The embryonic development of the egg is twice as rapid as that of the olive fly and it hatches before the latter (after 1 to 2 days).
- The neonate larva attacks the egg of B. oleae which it empties by suction.
A fungus, Sphaeropsis dalmatica (Macrophoma dalmatica), appears at the same time, introduced by the female of the midge at the time of egg laying. This develops to the detriment of the remains of the yolk of the B. oleae egg and then the fruit tissues. A characteristic oval mark appears on the surface of the olive.
The larva completes its development in 8 to 10 days, feeding on this fungus.
- pupa: once larval development is complete, it leaves the olive via the oviposition hole, drops to the ground and burrows beneath the soil, spins a cocoon and pupates.
Pupation lasts 7 to 8 days.

[R]Life Cycle
The species has 3 to 4 generations each year, until mid- to end of October. The winter is passed in the larval stage.

[R]Damage
The marks caused by the associated fungus are characteristic. Fruits then blacken and drop.

[R]Remark/A>
This midge has a curious status.
It is unquestionably a pest of early olives, causing damge mainly following introduction of the fungus.
On later olives, it is a beneficial insect (to be protected) because its larvae destroy many olive fly larvae.

[R] Images

1. Prolasioptera berlesiana Paoli Adult female (Drawing in Arambourg)