Melon fly

on a young cucumber, small melon or baby pumpkin, look for tiny puncture marks like pinpricks, often with a bead of clear or gummy sap weeping out and a small brown, sunken halo around each dot. This is where a female fly has jabbed in her egg-laying spike ("stung" the fruit) and slipped her eggs just under the skin.

a stung fruit grows crooked or lumpy, goes soft, and rots from the inside. Many young fruit then turn yellow and drop early — you find small fruits lying on the ground long before they should be there.

cut a suspect or fallen fruit open and you will find white, legless grubs (maggots) up to about 1 cm long wriggling in wet, brown, foul-smelling pulp. When you disturb them they can flick and jump off the flesh.

about the size of a housefly but orange-brown, with clear wings marked by dark brown bands along the front edge and a spot at the wing-tip, and pale-yellow marks on its back. It rests on the underside of leaves in the heat of the day and is busiest in the cool of early morning and late afternoon.

the many small flies crawling over an already-rotten fruit are usually harmless scavengers (houseflies and vinegar flies) that arrived AFTER the rot began — they are not the culprit. The melon fly attacks healthy, young, still-firm fruit, so hunt for the fresh sting on a good fruit, not the crowd on a spoiled one. A plain grey housefly with clear, unmarked wings does not sting fruit at all.

start checking the moment tiny fruit begin to form behind the flowers (fruit-set) and keep going right up to harvest. This fruiting stretch — the mid to late part of the season — is exactly when the flies attack. Warm, sticky-humid weather makes it worse, so look harder then.

put up at least one cue-lure trap per plot — a smell-bait that pulls in the male flies so you catch them before you ever see fruit damage. Check the trap once a week and write the number down so you can watch it rise or fall.

melon fly builds up explosively, so do not wait for a crowd. Act the day your trap catch is higher than the week before, OR the moment you find even ONE young fruit with a fresh sting. By the time you can find several stung fruit, eggs are already laid inside where you cannot reach them.

twice a week, walk a "W" shape across the plot so you cover all four corners and the middle, not just the row nearest the path. Make about 10 stops along the way.

(1) the skin of young fruit for fresh punctures and sap beads, (2) any fruit already lying on the ground, and (3) the underside of shaded leaves for resting orange-brown flies. Cut open any suspect or dropped fruit to confirm the maggots inside.

hang cue-lure traps across the plot to mass-trap the male flies; the smell-bait draws them in, and with the males caught, fewer females can breed. Spread several traps over the block, and get your neighbours trapping too — one garden alone cannot hold back flies that drift in from all around.

the one recommended spray is a protein bait spray — dabs of protein food mixed with a small amount of killer, placed as spots or short bands on the leaves, never on the fruit you will eat. The adult flies come to feed on the bait and die before they can sting the fruit. This beats blanket-spraying the whole field, which does not work here, because the maggots sit hidden inside the fruit where no spray can reach them.

cover your skin, eyes, nose and mouth; spray in the cool of early morning or evening with the wind behind you; keep the bait well off food, drinking water, children, animals and bees; and after finishing, wash yourself and your clothes. Always wait the full pre-harvest interval — the set number of days between spraying and picking or eating the fruit — before you harvest. If you ever mix a stronger insecticide into the bait, switch to a different type each time so the flies do not become resistant (stop being killed by it).

if trap catches and stings keep climbing, do everything at once and rope in your neighbours — daily clean-up, bagging, traps and bait sprays across all the plots together, because one neglected garden re-seeds the whole area. If a fruit is already soft, crooked and maggoty it cannot be saved — strip ALL infested fruit off the vines, gather every fallen one, and bury or destroy the lot, then deep-plough to kill the pupae in the soil. You lose that fruit, but breaking the breeding cycle now protects your next crop — and your neighbours'.