Understanding the life cycle of the fruit fly can tell you a lot about how the pest can best be controlled in the home garden. The actual methods you can use to control fruit fly, and the ways these can be used together is based on an understanding of its life cycle. Without an understanding of the life cycle of fruit fly, you may end up using control methods in a way that fail to solve your pest problem. Having a basic understanding of the life cycle of fruit fly can help you determine:
- how a particular life stage affects your crop
- when the pest is likely to be present, and of the greatest threat to your garden
- when the pest is most susceptible to control and for how long
- how a particular life stage is affected by a control method
- how you can create unfavourable conditions for the pest in your garden
- when it is too late to control
Stages of the life cycle
There are four stages to the life cycle of fruit flies, these are: eggs, larvae (maggots), pupae and adults. A brief description of each of the stages of the life cycle of fruit fly is provided below. Note that the life cycle of most fruit flies (Tephritidae) species is similar.
The female adult fly lays eggs (1-20) into the maturing and ripening fruit of the host plant. The eggs hatch into larvae inside the fruit after a few days (2-4 days). Note that at this stage of the lifecycle you are unlikely to be able to recognise the presence of fruit fly eggs in your fruit.
The hatching larvae (maggots) feed on the flesh of the fruit, gradually moving towards the centre of it. The feeding activity of the larvae causes the fruit to prematurely ripen and rot. The larval stage is the most likely stage that you would recognise the presence of fruit fly in your fruit if you cut it open.
As the fruit ripens and rots, it falls to the ground. Fully mature larvae leave the fruit and burrow into the soil to pupate. In the soil, larvae become inactive and change into oval, light to dark brown, hard pupae, in which adult flies develop. At this stage you are unlikely to recognise the presence of fruit fly pupae in the ground.
The adult flies may emerge from the pupae in as little as seven days during the summer, or after several months over winter. The adult fly looks for the nourishment it needs to reach maturity, breed, and lay eggs in new season crops. At this stage of the lifecycle you may be able to recognise adult flies landing on or hovering around fruit.
Behaviour of fruit fly
Fruit fly numbers tend to increase, usually in spring, when temperatures are warm and there is continued availability of suitable host plants. Fruit flies develop from eggs to adults within four to five weeks.
Adult flies (both male and females flies) usually:
- are most active from October to May (some activity will occur in warmer periods during the winter months)
- are most active from dawn to the first few hours of the day
- rest in shady trees (fruit trees, ornamental trees and shrubs) during the day
- feed in the host tree
- mate at dusk
- are strong fliers and can travel some distance
- can survive throughout winter
Female fruit flies usually:
- lay eggs into healthy, maturing and ripening fruit (on the tree) and vegetables
- need to feed on a source of protein before eggs will mature for laying
- only mate once in lifetime
- must wait about five days before commencing egg laying
- reabsorb egg during extended periods of cold weather