Fruit Fly
Apr 2025: A Quarantine Area Notice is in effect in Perth's southern suburbs to eliminate a recent incursion of Queensland fruit fly (Qfly). Please visit DPIRD's website to find out if you are in the quarantine zone and what your responsibilities are.
This page discusses Meditteranean fruit fly (Medfly), which is an established declared pest.
Mediterranean Fruit Fly is currently a declared pest only in the local government area of Serpentine-Jarrahdale.
About
The Mediterranean fruit fly (Ceratitis capitata), often referred to as Medfly, is a significant threat to horticulture. It attacks a wide range of cultivated fruits and some fruiting vegetables.
Female Medflies lay eggs into ripe fruit, leading to larval infestations that damage the fruit. Infested fruit may appear bruised with broken flesh. Both fruit on the ground and in trees are susceptible to Medfly larvae.
Proper maintenance of fruit trees can prevent the infestation and spread of Medfly. Recommended practices include removing unwanted or non-commercial trees, disposing of fallen fruit, eliminating unharvested fruit from trees to reduce breeding sites, and properly disposing of infested fruit to break the breeding cycle.
Monitoring for the presence of Medfly can be achieved using traps, and several control options are available.
Control methods
Chemical
The Department of Primary Industries and Regional Development (DPIRD) recommends two primary chemical control techniques:
Baiting: this involves applying a mixture of an attractant (usually a protein source) and an insecticide to parts of the tree or surrounding vegetation. Female Medflies are attracted to the bait, consume it, and are killed by the insecticide. Baiting should start during the early stage of fruit development, when the fruit is about one-third of its final size, and continue until all fruit has been harvested. Regular reapplication is necessary, especially after rain.
Lure and kill: this method uses devices that attract Medflies with a lure and then expose them to an insecticide. These devices can be hung in trees and are particularly useful for monitoring and reducing Medfly populations. Combining lure and kill devices with baiting can enhance control effectiveness.
Physical
Physical control methods for fruit fly should be combined with chemical and biological control strategies for maximum effect.
Fruit removal: Regularly collect and dispose of fallen and unharvested fruit to eliminate Medfly breeding sites.
Exclusion netting: Fine mesh netting over trees or individual fruit prevents adult flies from laying eggs.
Bagging fruit: Cover individual fruits with paper or cloth bags to protect them from infestation.
Mass trapping: Deploy baited traps to attract and capture adult Medflies, reducing their population.
Pruning and tree maintenance: Keep trees well-pruned to make monitoring and control easier while reducing excess fruit.
Biological
DPIRD has implemented the Sterile Insect Technique (SIT) as a biological control method for Mediterranean fruit fly.
Monitor and report
Monitoring is an essential part of any fruit fly control program and can provide information on seasonal abundance patterns and hotspots.