Help prevent overwintering of Queensland fruit fly

Winter is here! Although we can hope for some cold days and frosts to help kill off adult Queensland fruit fly that have bred up in high numbers over autumn, it is better if we can take matters into our own hands and reduce their numbers.

The La Nina weather event and numerous commercial factors have resulted in unharvested fruit and a difficult season for many commercial growers. These factors aided in fruit fly numbers in autumn being one of the highest on record for this time of the year.

As deciduous trees and vines lose their leaves and are exposed to the elements, fruit flies will look for shelter and protection from the cold weather. Spreading evergreen trees with large leaves (e.g. avocadoes, citrus, loquats, or native vegetation) may be a safe refuge as cold weather sets in.

They provide a warmer area with protection from heavy frosts, rain and cold winds, moisture and protection from predators. Temperatures within the canopy of a tree can register as high as 5-7°C when the temperature outside is at 0°C. Flies will also look for refuge around buildings (e.g. sheds and houses that are heated during winter). Baiting these trees during later winter late July - August is a good way to reduce the number of over wintered flies.

  • Adult Queensland fruit fly survive for up to four months in the cold weather, compared to less than two months in summer.
  • Look out for the lemon tree near the house or packing shed this is an ideal place for fruit fly to over winter.
  • Wind breaks of olive or avocado trees provide a safe harbour for fruit flies over winter.
  • Don’t be fooled by no flies in traps over winter - fruit flies are less active over in cold weather and will not move around much. In fact if the temperatures is 2-3°C or below, fruit fly are unable to move ('torpid') so you might not see them in the traps it doesn’t mean they are not there. If there are a few sunny days in winter we will see flies in the traps.
  • Baiting refuge trees during winter (late July – August) is a good way to reduce the number of over wintered flies.
  • Getting on top of the spring peak is the key to next season's control.

Find out more about controlling Queensland fruit fly.

Source: Greater Sunraysia Fruit Fly Regional Advisory Group update (Andrew Jessop and Narelle Beattie)

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