Delia antiqua

Onion fly

What is Onion fly?

The onion fly (Delia antiqua), also referred to as the onion maggot, is a frequent pest that harms allium plants, including leek, garlic, and onion crops. It is a small fly, measuring between 5 and 7 mm long, with a grayish-yellowish body and clear wings.

The eggs are laid by the female onion fly on the young leaves, necks of onion seedlings or in the soil close to the base of onion plants. The onion fly larvae that emerge from the eggs tunnel into the onion bulbs, harming the roots and foliage. This leads to retarded growth, decreased yield, or even death of the plant.

For onion growers, onion fly infestations can be a major concern, but there are a few control strategies that can be used to manage this pest. These include crop rotation, planting resistant varieties, using biocontrol agents, and applying chemical insecticides when necessary.

Recognize onion fly infestations

It can be difficult to identify an onion fly infestation because the signs may not always be visible. But there are a few symptoms to watch out for. The wilting or yellowing of onion leaves is one of the most obvious signs of onion fly damage. Small tunnels made by the larvae as they feed can also be seen in the bulbs. The bulbs may occasionally soften or decay, which may be a sign of a serious infestation. Regularly checking your onion plants for these symptoms is essential since spotting an infestation early can help stop the insect from spreading and causing more harm.

Damage caused by onion fly

Severe onion fly damage can cause stunted growth, yield reduction or even death of the onion plant. The roots and leaves are harmed when the onion fly larvae tunnel into the onion bulbs. This damage may decrease the quality of the onion bulbs and make the plant more vulnerable to other diseases and pests. Severely damaged bulbs may turn soft or decay, making them unsuitable for consumption.

Biological control of onion fly with nematodes

Biological control using nematodes can be an effective strategy to manage onion fly (Delia antiqua) infestations. Steinernema feltiae is a beneficial nematode species that is effective natural enemy of onion fly larvae. These nematodes are applied by spraying. After application, the nematodes set out in search of the larvae, eventually killing them. The fact that this biological control strategy is safe for people and non-target organisms gives various advantages over chemical control. It's crucial to remember that nematode treatments are more effective when used in conjunction with other pest management strategies including cultural practices and chemical control. Additionally, proper application of nematodes is critical for their success, so it's important to carefully follow the instructions when using this strategy of onion fly control.

Effectively apply nematodes to control onion fly

Success of onion fly control starts with the right approach. Growers must carefully monitor the development of the onion fly. This way he knows when the first flight of the onion fly is coming. After that apply Capirel twice, with an interval of eight to ten days. Then most onion fly larvae will die, and the pest pressure will remain low.

Finally, the correct application of the nematodes is important. The soil must be damp, bright sun must be avoided, as well as a lot of wind otherwise the product dries up too quickly. So, spraying late in the afternoon will have the most effect. And yes, you can even spray during a rain shower. Then the nematodes are washed immediately into the soil.