Onion MaggotsOver fifty years ago, a western New York grower discovered that early radishes are preferred to onions by the onion maggot! To test his observation, he sowed radishes in several experimental blocks of onions and found that the roots became maggoty whereas the onions near them were practically free from infestation. Because of his success he now uses radishes regularly as a trap crop for the maggots. He is convinced that even though he were to gather and burn the radishes the practise pays because of the larger proportions of marketable onions produced. Probably the continued destruction of the trap crop will reduce the size of later broods the same year and in following years.
Onion maggots are the laws of flies nearly related to house flies. They spend the winters mostly in buildings, though some remain in the ground. In early spring the females lay eggs on onion seedlings and sets. A few days later the grubs hatch and gnaw their way into the young plants. Rot and wilting soon follow. By the end of May or early June in southern New York the maggots mature, pupate and emerge from the ground as fully grown flies which soon lay eggs for a second brood. In some parts of the country it is believed there is a third brood. Control of the first brood is most important because it lessens the number of insects in the second brood and consequently reduces the damage.
Adapted from: Gardening Short Cuts
See Also: Garden Pests