RHS Leaflet Pear Fruitlet Gall Midge
Some good information here. I haven't found it to be the case that mid-season varieties are unduly affected, two of the earliest to flower (Morettini and Devoe) have been the worst affected this year. There is definitely a marked difference in susceptibility in some varieties, as adjacent cultivars flowering at exactly the same time have remained unaffected. Now that an infestation pattern seems to be emerging, I will probably consider spraying the most susceptible varieties next year, as pear midge can eventually result in significant losses. Whether spot treatment of affected varieties only will be effective in reducing adult midge numbers remains to be seen.
The usual un-informed musings from the team. It much easier to control the maggots BEFORE they emerge and crawl off into the environment (see below for further reasons why leaving the maggots in situ to cause maximum damage isn't a good idea). I see no evidence that it is a self-limiting problem; in my experience it tends to increase in severity over time particularly where control is lax or difficult.
Excellent information here (particularly re. the mobility of the larvae in the environment). Very interesting to read that the presence of infected fruitlets can have a negative effect on the development of the unaffected percentage of the crop; I've certainly found this to be the case on my in-laws' Conference which invariably loses the whole crop by June. Most plant Galls are triggered by chemicals secreted by the infecting larvae, which deliberately encourages abnormal excess growth. Yet another reason to exercise vigilance and remove all affected fruitlets as early as possible.
Re. 'biological controls' I have to say that poultry don't appear to have much effect on mopping up midge grubs, or any other pests for that matter; the last place my hens ever want to scratch around is in the vegetable garden or under fruit trees.