Despite the unfounded concerns of some gardeners, setting up Queensland fruit fly traps will not attract more of the harmful female pests into your garden.
These traps do work effectively to reduce the numbers of the pest already there, and are best installed at the start of spring (September), before fruit and vegetables develop. These pests will attack fruit as small as a marble!
There are two types of traps that are used in the control of Queensland fruit fly, these are:
- Synthetic pheromone-based traps, which only attract and control male Queensland fruit flies.
- Sugar-protein traps, which attract and control both male and female Queensland fruit flies.
Let’s look at both of these traps in detail and outline the important differences.
How Far Do Pheromone Traps Attract Queensland Fruit Fly?
The synthetic pheromone traps only attract male Queensland fruit flies, and are long-range traps that will attract them from up to 400m away, which is a fair distance, but keep in mind that the males don’t damage crops by laying eggs in fruit and vegetables, the it’s the females that do.
Eliminating the males prevents them breeding with the females, who need to mate to become fertile, after which they can sting fruit and vegetables to lay their eggs inside.
It doesn’t really matter how many males are attracted into the garden, they’re just sugar/nectar feeders and don’t do any harm, and if traps attracts them away from females, all the better.
It only takes one surviving male Queensland fruit fly to mate with hundreds of females though, which is why we can’t rely on just male traps alone to reliably control this pest.
How Far Do Sugar-Protein Traps Attract Queensland Fruit Fly?
The Queensland fruit fly traps which attract both males and females contain a sugar-protein mix. This is because all adult Queensland fruit flies feed on sugars to stay alive, but the females also need to consume protein before they can become sexually mature to mate. They usually source protein from bacteria on leaves (which proliferate during warm, humid conditions), animal droppings and juices in fruits, and that’s why it’s important to clean up after pets, and to collect fallen fruit!
Unlike the synthetic pheremone traps which only attract male Queensland fruit flies, and work up to 400m away, the sugar-protein traps which attract both males and females, and are needed to control the female pests which do the actual damage to crops, are only short-range traps that don’t attract the pests very far at all.
The setup instructions of commercial sugar-protein Queensland fruit fly traps recommend setting up 1 trap per tree or 1 trap every 20m2 when trees are touching. With one trap every 20 square metres, three or four traps would required to cover a 60-80m2 garden planted up with fruit trees or vegetables, due to the short attraction range of these traps. To put it another way, unless you have a tiny courtyard under 20 square metres in size, you’ll need more than one sugar-protein trap which attracts females just to cover your own back yard, as they don’t have enough reach to draw in pests from further away.
With the expense of commercial sugar-protein Queensland fruit fly traps, if buying several is cost-prohibitive, then consider building your own, they cost almost nothing, making it cost effective to protect fairly large areas.
To learn how to make your own DIY home-made traps for next to nothing, see article – How to Make a Queensland Fruit Fly Trap and Bait
For detailed instructions on every method available to control this pest, see article – How to Control Queensland Fruit Fly in the Home Garden, An Integrated Pest Management Approach
More articles on Garden Pests, Diseases and Problems
I used to hang fruit fly traps on my olive trees, but they attracted more flies and increased the fly population around the trees. Since not all flies ended up in the traps, remaining ones were enough to cause more damage. Many farmers in the area believe that pesticides and fly traps fail for the same reason.
I would guess that since there are a finite number of fruit flies in the garden, and since traps have a limited range that they work to attract the pests, when they’re all gathered around the traps, there’s the same number in a smaller area, which means their population becomes denser there, making them appear greater in number. If the flies are not ending up in the traps, that would suggest that the bait is not effective or no longer efefctive, and may need to re replenished with fresh bait if it was working before, or changed to a different bait if it’s not working well from the start.
One alternative may be to hang the traps at a reasonable distance from the trees that we want to protect so that flies congregate away from where we do not want them. In the place where I live there are many hectares of tangerine orchards which create a population of Mediterranean fruit flies, large enough “close” to infinity – mathematically speaking, a few minus infinity 🙂
With any trapping pest control measures its probably easiest to understand it from a strategic Integrated Pest Management (IPM) perspective. The amount of the crop, which is attracting the pest, will always greatly outnumber any traps present. The traps divert the pests away from the plants that attracted them there, and they usually use baits that just smell like over-ripe or fermenting fruit. Hope that helps! 🙂