Fruit flies

tiny sting punctures on the skin of ripening fruit, each with a bead of clear sap or gum oozing out that later darkens into a soft, sunken brown spot. The flesh beneath rots, the fruit ripens unevenly and drops early, and when you cut a suspect fruit open you find small white maggots tunnelling in the pulp.

white, legless and tapered like a tiny grain of rice, up to about 1 cm long. Disturb one in cut fruit and it can suddenly flip or "jump" into the air — a trick no ordinary grub does.

about the size of a housefly (~8 mm), slender and shiny brown-black, with two bright yellow patches on its "shoulders" just behind the head, and clear wings crossed by a dark stripe along the front edge. It struts over fruit and leaves in warm daylight, often flicking its wings; the female carries a pointed tail she jabs into the fruit to lay her eggs.

with the common housefly: a housefly rests with its wings folded flat over its back and never stings fruit, while the fruit fly holds its wings out to the sides and shows those yellow shoulders and banded wings. And tell a fruit-fly sting apart from a bird peck or a knock bruise — those don't ooze first and then rot from the inside. A fruit-fly sting is a pinprick with an ooze bead that later hides maggots within, not one big chewed or broken hole.

start as soon as the fruit begins to size up and change colour — the mid-to-late fruiting stage — because that is when the females start stinging; hard green fruit does not yet attract them. Warm, humid spells sharply raise the danger, so check more often then, and keep checking right through to harvest.

put up a few methyl-eugenol traps (methyl-eugenol is a scent lure that pulls in the male flies) or protein food-bait traps in the shaded canopy — at least 3 to 4 spread around the orchard — and write down the catch from each one every week so you can see whether the numbers are climbing.

cross the block in a big "W" so you cover all four corners and the middle, not just the row beside the path. Make about 5 stops, and at each stop check 10 ripening fruit — about 50 fruit in all — for sting marks, oozing beads and soft spots, cutting open 2 or 3 suspect fruit to look for maggots.

Even 1 stung fruit with an oozing puncture in your sample, or a weekly trap catch that has climbed above last week's, means the flies are active and laying → act now. Don't wait for more: once the maggots are inside the fruit, no spray can reach them.

twice a week, gather up every fallen and stung fruit, from the ground and off the tree, and destroy it — bury it at least knee-deep (about 50 cm) so the flies inside cannot dig back out, or seal it in a black plastic bag left in the sun for a week, or boil or burn it. This starves the next generation, because the maggots crawl out of dropped fruit into the soil to become new flies. Also bag your high-value fruit (mango, guava) in paper or net sleeves once it sets, and pick at the right maturity instead of leaving ripe fruit hanging as a breeding site. Do this together with your neighbours — flies cross fences.

hang male-annihilation blocks through the orchard — a wick or block soaked in the male lure (methyl-eugenol) plus a killing agent — so they draw in and kill the male flies, leaving the females unmated to lay far fewer eggs. Add protein food-bait stations that both males and females come to feed on. And protect the tiny parasitic wasps — natural helpers that lay their own eggs inside fruit-fly maggots and kill them — by avoiding broad, whole-tree sprays that wipe them out.

if stings keep appearing, use a protein bait mixed with spinosad (spinosad is a low-toxicity insecticide made from a soil microbe) — but dab it as a patch on the shaded side of each tree, NOT a full cover spray over the whole canopy. The flies come to feed on the bait and die, while bees and helpful insects are largely spared. Safety: cover your skin, eyes, nose and mouth; spray in the cool of morning or evening with the wind at your back; keep it away from food, drinking water, children and bees; and respect the pre-harvest interval — the number of days the label says to wait between spraying and picking — before you eat or sell the fruit, then wash yourself and your kit afterwards. Resistance: don't lean on one product — rotate to a different type of bait from time to time, and keep the traps and sanitation going, so the flies never get used to it.

If fruit keep getting stung despite traps and bait, treat it as a neighbourhood problem — fresh flies are flying in from unmanaged trees nearby — so get every neighbour burying fallen fruit at the same time, and strip and destroy ALL remaining infested fruit to break the breeding cycle. On badly hit trees, pick the sound fruit a little early at proper maturity rather than lose it to fresh stings, and accept the loss on the rotten and dropped fruit. Then keep destroying every dropped fruit right through the season, so the next flush comes up clean.