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Ministry of Agriculture, Food and Rural Affairs

Pear Blossom Midge

Blossom midge damage Blossom midge damage Blossom midge damage Blossom midge damage Blossom midge damage Blossom midge larvae Click to enlarge.

Beginner

This pest affects:

Pear;

Scientific Name
 Contarina pyrivora

Identification
Eggs

  • Very small
  • Spindle-shaped
  • Semitransparent white

Larvae

  • Small, yellowish-white grubs
  • Typically, found in multiples inside pear fruitlets
  • When fully grown they are 4-5mm long
  • Mobile, flick themselves along by flexing their bodies

Adults

  • 2.5-4 mm long
  • Greyish black fly with yellow hairs on thorax
  • Newly emerged female abdomen pale brownish yellow
  • Wings have few veins and are dusky with fine black hairs
  • Bead-like antennae of male elongate, but those of female relatively short

Damage

  • Infested fruitlets grow faster  and are often softer than healthy ones initally
  • Fruit becomes rounded or malformed
  • During May they begin to turn black at the calyx end of the fruit
  • Infested fruitlets cease development about 20mm in diameter, turn black starting at the calyx end,  before dropping from tree
  • Healthy fruit may also drop due to fast-growing infested fruits diverting nutrients
  • Very heavy crop loss will follow

Often Confused With
Frost damage – no larvae or blackened cavity inside distorted fruit

Period of Activity
Early spring during bloom. The critical period for chemical control begins when the sepals have spread apart enough to show the first appearance of pink (the folded petals underneath), and continues until just before most of the blossoms are open.

Scouting Notes
Be aware of any past problems of pear blossom midge in any given block.

Threshold
No threshold established.

 

Advanced

This pest affects:

Pear;

Scientific Name
 Contarina pyrivora

Identification
Eggs

  • Very small
  • Spindle-shaped
  • Semitransparent white

Larvae

  • Small, yellowish-white grubs
  • Typically, found in multiples inside pear fruitlets
  • When fully grown they are 4-5mm long
  • Mobile, flick themselves along by flexing their bodies

Adults

  • 2.5-4 mm long
  • Greyish black fly with yellow hairs on thorax
  • Newly emerged female abdomen pale brownish yellow
  • Wings have few veins and are dusky with fine black hairs
  • Bead-like antennae of male elongate, but those of female relatively short

Damage

  • Infested fruitlets grow faster  and are often softer than healthy ones initally
  • Fruit becomes rounded or malformed
  • During May they begin to turn black at the calyx end of the fruit
  • Infested fruitlets cease development about 20mm in diameter, turn black starting at the calyx end,  before dropping from tree
  • Healthy fruit may also drop due to fast-growing infested fruits diverting nutrients
  • Very heavy crop loss will follow

Often Confused With
Frost damage – no larvae or blackened cavity inside distorted fruit

Biology
The pear midge overwinters in silken cocoons as a pre-pupae in the soil, and the adults emerge mid- to late spring. The first flies will generally appear when Bartlett and Clapps are in the tight cluster bud stage and egg-laying occurs at the white bud stage.  The adults are active up until Bartlett full bloom. Eggs, usually from 10 to 30, are deposited in bud or blossom, usually in groups on the anthers. Larvae hatch in 4-6 days and feed inside the fruitlets, forming a black cavity at the calyx end. In about 6 weeks, fully mature larvae may leave the fruit or remain inside until it drops to the ground. In June and July, the maggots exit from the fruit (on the tree or the ground) and burrow into the soil as much as 5-8 cm to overwinter. There is one generation per year.

Period of Activity
Early spring during bloom. The critical period for chemical control begins when the sepals have spread apart enough to show the first appearance of pink (the folded petals underneath), and continues until just before most of the blossoms are open.

Scouting Notes
Be aware of any past problems of pear blossom midge in any given block.

Threshold
No threshold established.

Management Notes
Pick off all infested fruitlets in May or early June, and destroy them with the maggots in them. This is very labour intensive and most appropriate for organic production.

There are no products registered for pear blossom midge control.  It is usually controlled by chemical applications for other pests at the immediate pre-bloom period.  In most cases of fruit infestation, the problem comes down to the proper timing of an effective insecticide spray at white bud.

Some information included above has been excerpted from;

http://www.which.co.uk/documents/pdf/pear-midge-153689.pdf

http://www.scaffolds.entomology.cornell.edu/1999/4.12_insects.html#midge