Fruit fly
The maggot works from inside the fruit — by the time the fruit rots and drops, the damage is done. Trapping and sanitation beat spraying.
- Pest type
- Fly (maggot in fruit)
- Attacks
- Maturing / ripening fruit
- Worst in
- Warm, humid fruiting season
- Main risk
- Hidden maggots; fruit drop
Overview
Fruit flies are the most damaging pest of mango, guava and the cucurbit vegetables. The adult female punctures the skin of maturing fruit with her ovipositor and lays eggs just under the surface; the hatching maggots tunnel through the pulp, feeding from the inside out.
That hidden feeding is what makes the pest so costly — the fruit looks fine from outside until oozing sting marks, soft rotting patches and premature drop reveal it, by which point the produce is unsaleable. Because the maggots are protected inside the fruit, cover sprays are largely wasted; control depends on trapping the adults, killing them with bait before they sting, and destroying fallen fruit to break the cycle.
How to identify it
- Small brown-yellow flies (a little smaller than a housefly) around ripening fruit, often with clear patterned wings.
- Tiny puncture/sting marks on the fruit skin, sometimes oozing a drop of sap that dries to a brown speck.
- Soft, rotting, sunken patches and premature fruit drop; cut a dropped fruit open and you find white legless maggots tunnelling the pulp.
- In cucurbits, young fruit rots and drops; in mango and guava the loss peaks as the fruit ripens.
The damage it does
- Maggots tunnel and rot the pulp from inside, so fruit collapses and drops — often after it looks fully formed and nearly ready.
- Sting marks and internal rot make even standing fruit unsaleable and unfit to eat.
- Heavy losses in mango, guava and cucurbits — often the single largest source of fruit loss in the season.
- Fallen infested fruit lets the maggots pupate in the soil and re-emerge, building the population cycle after cycle.
When to act
- Hang methyl-eugenol traps well before the fruit starts to mature, and count the catch to know when adults arrive and peak.
- Start control at fruit set to early maturity — once maggots are inside the fruit, nothing sprayed on the outside will reach them.
- Collect and destroy dropped fruit daily through the season; skipping this undoes everything else.
Organic & cultural control
- Sanitation is the backbone — pick up and deep-bury or solarise all fallen and stung fruit so maggots cannot pupate in the soil and return.
- Hang methyl-eugenol (para-pheromone) traps to mass-trap and monitor the males; several per acre through the fruiting season.
- Bag individual fruit (mango, guava) with paper or fruit-protection bags where practical — a physical barrier the fly cannot sting through.
- Ploughing the orchard floor exposes soil pupae to sun and predators; harvest at the correct maturity rather than over-ripe on the tree.
Chemical control
- Use protein/bait sprays, not cover sprays — a bait of protein hydrolysate plus an insecticide, spot-applied so the flies feeding on it are killed before they sting.
- CIB&RC-registered insecticides used in traps and bait stations (e.g. with methyl eugenol) are the standard approach; follow the label and your local recommendation.
- Blanket insecticide cover sprays are largely wasted against maggots protected inside the fruit and are best avoided.
- Confirm the current recommendation for your crop and area with your local KVK — trap-and-bait programmes are area-wide and work best community-wide.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
My mangoes/guavas rot and drop just as they ripen. What is causing it?
Almost certainly fruit fly. The female stings the maturing fruit and lays eggs under the skin; the maggots tunnel the pulp from inside, so the fruit rots and drops just as it nears ripeness. Cut open a dropped fruit and you will find white maggots. Methyl-eugenol traps plus strict removal of fallen fruit are the fix.
Why do cover sprays not control fruit fly?
Because the maggots live inside the fruit, protected from anything sprayed on the surface. Effective control targets the adult flies instead — methyl-eugenol traps, protein-bait spot sprays that flies feed on, fruit bagging, and above all collecting and destroying fallen fruit so the next generation cannot emerge from the soil.
How important is picking up fallen fruit?
It is the single most important step. Maggots leave dropped fruit and pupate in the soil, then emerge as the next wave of flies. If fallen and stung fruit is collected and deep-buried or solarised daily, you break that cycle — skip it, and traps and baits alone will not keep up.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.