Onion maggots burrow into onions during the growing season either killing the plant or making it unfit to eat. The cabbage maggot not only feeds on the roots of cabbage, but also attacks the roots of radishes, turnips, rutabagas, beets, cauliflower, broccoli and Brussels sprouts, either killing the plant or reducing their vigor. The adults of these maggots are small flies which lay their eggs at the base of the plants. After the eggs hatch, the maggots move down into the soil and start eating on the plants . Several generations will occur each year but most of the damage is done by the first generation.

Control of these insects should be accomplished at planting time. Several formulations of Diazinon can be used for effective control of root maggots. Diazinon granules will give the best control. Other insecticides labeled for root maggots such as Tempo can also be used, but only for plants listed on the label. The active ingredient in Tempo is available in Bayer Advanced Garden Multi-Insect Killer.  The insecticide should be applied into the open furrows or holes at planting time. One treatment may be sufficient for radishes but with the other vegetables re-treatment may be necessary three to four weeks after the initial treatment. Follow label directions when applying insecticide.

This page was last updated April 2003

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