Queensland Fruit Fly Outlook – December 2025

This information has been commissioned by the Goulburn Murray Valley Area Wide Management Fruit Fly Program and is funded by the Victorian Government. Use of this material in its complete and original format, acknowledging its source, is permitted, however unauthorised alterations to the text or content is not permitted.

Summary

December is the time when Qff populations commence their annual build up in the GMV. Weather forecasts for the GMV suggest that Qff buildup may be reduced due to warmer maximum temperatures and less rainfall than usual in December 2025 and January and February 2026. Population reduction can be further achieved by increasing fruit fly management that commenced in spring. Continued active management is necessary to avoid population build up in late summer and autumn when most of the GMV’s crop ripen.

Trends

Overall fly numbers

New male-targetted fruit fly traps were deployed throughout the GMV during December 2025. No data have been collected as yet. Going on yearly fruit fly population trends from 2017 to 2024 it is highly likely that the fruit fly numbers found in traps are on the rise (Fig. 1)   – meaning that fruit fly populations, including eggs, larvae, pupae and adults present on the landscape are increasing drastically (Fig. 2).

NOTE re unfavourable weather conditions: Under these conditions a high percentage of adult Qff find refuge until more favourable conditions return. However, a high proportion of immature stages (eggs and larvae and, to a lesser extent, pupae) are killed off by hot, dry weather. Unless controlled by consistent farm and community management the adult Qff in refuge can then feed a late summer/early autumn Qff population explosion – which coincides with the bulk of commercial crop ripening.

NOTE re seen and real presence of Qld fruit fly in the GMV: One female Qff after mating just once with a male Qff can lay up to about 2,000 eggs which can produce around 800 sexually mature adult Qff. So, what can be seen in fruit fly traps – which capture only ADULT MALE QFF – is only hiding the reality: that the whole Qff population, if you include eggs, larvae and pupae – which are all unseen until it’s too late to control – is many, many times larger.

Fig. 2 demonstrates that, when effective area-wide mange strategies are not in place, the whole Qff population can be much, much higher than that perceived when traps are checked. The real population of Qff, including adults, eggs, larvae and pupae increases in size dramatically during December, dies off a bit in January if it’s hot and dry, and then increases drastically again in early autumn – just in time for ripening of the bulk of commercial horticulture in the GMV.

Again, Qff management strategies, if implemented correctly, will reduce Qff buildup by removing unwanted fruits and fruiting plants, netting useful crops, baiting and spraying.

Hot spots

Table 1 shows that, on average, by late December each year some towns have larger Qff populations than others. This is reflected by the volume and type of Qff host plants in each location as well as the level of fruit fly management being employed there.

People living in all areas should be vigilant in checking traps and for fruit infestation especially in locations with more than 2 Qff trapped per fortnight.

Tip: make sure your traps are charged with new lures and are not damaged. Otherwise replace. Also make sure that the traps are clear of foliage and branches and out of the sun in the hottest part of the day.

Tip: Make a habit of checking any nearby fruit for sting marks and/or infestation with maggots – even if the fruit is a roadside feral plant. If there are signs of infestation remove the fruit or the entire plant if you can.

Table 1. Average Qff per trap per fortnight at several locations for the period from August to December (2017 to 2024)

Land use type

On average, by December, urban trap sites are still the main source for higher populations of Qff when compared to peri-urban and rural location (Fig. 3). As urban fruit ripens and drops, is harvested or is eaten by birds Qff will migrate from urban areas into peri-urban sites and then into commercial crops.

Tip: There is a high degree of responsibility for urban gardeners to reduce Qff populations in their yards not only to produce good quality fruit in their own gardens but also to reduce the influx of Qff into other areas – especially commercial orchards.

Forecast

In the GMV, fruit fly numbers generally increase in severity from late November and peak in December with a second peak in the autumn. Qff builds up very rapidly in urban and peri-urban sites with a mixture of high amounts of untended fruit, garden irrigation and evergreen refuges while rural sites remain quite low as there is still not much ripe fruit around. Rural sites with high Qff numbers at this time are likely to have persistent Qff populations surviving in untended home gardens and untended non-commercial fruit trees on the block.

Tip: Even if your commercial crop is well-managed with respect to Qff you must ensure that all other fruiting plants in and near your orchard are well-managed (or removed), too. Qff will move from the old apricot tree in the fowl yard into the next ripening crop nearby.

As urban crops decline with harvest and bird predation in the summer Qff populations also decrease while peri-urban and rural increase. This reflects the movement of Qff from urban, through peri-urban and into rural areas from mid-summer to autumn. This occurs due to the “pull” of large volumes of commercial crops ripening in rural areas at this time.

It is expected that similar trends will occur during 2025/26. The size of the peaks and their timing will depend on weather and fruit fly management measures implemented during the spring and early summer.

Weather

The Bureau of Meteorology  (http://www.bom.gov.au/climate/outlooks/#/overview/summary/ – accessed 10 December 2026 – Figs 4, 5 and 6) forecasts higher than average maximum temperatures (greater than 80% chance of being higher than the average of 27°C to 30°C) and higher than average minimum temperatures (60% to 65% chance of being higher than the average of 12°C to 15°C) for December 2025 and January and February 2026 in the GMV. Rainfall is likely to be lower than average with only a 25% to 30% chance of being higher than the average of 100mm to 200mm.

Forecast weather conditions for Shepparton for the 15 days from 10 December 2025 (https://www.visualcrossing.com/weather/weather-data-services – accessed 10 December 2025) indicate likely high temperatures, low humidity and very little rainfall (Table 2). This could be detrimental to the survival capability of adult Qff as well as immature life stages – especially if infested fruit fall to the ground and are subsequently exposed to the sun. At these temperatures eggs and larvae will die. Eggs and larvae in fruit in the shade and on the tree may survive.

Adult Qff, however, are quite resilient and if not exposed to the sun will fly to cooler, more humid locations in bushy evergreen foliage if they can – often during the cooler late afternoon. Low humidities will reduce their ability to fly long distances.

This suggests that Qff populations may be impacted adversely during the early summer. Vigorous area-wide management programs will enhance Qff control significantly if set in place.

Table 2. Forecast temperatures and rainfall for Shepparton for the 15 days from 10 December 2025 (https://www.visualcrossing.com/weather/weather-data-services – accessed 10 December 2025).

Fig. 4. Chance of above median rainfall for December 2025 to February 2026

Fig. 5. Chance of above median maximum daily temperature for Dec 2025 to Feb 2026

Fig. 6. Chance of above median minimum daily temperature for Dec 2025 to Feb 2026