Onion Fly: How to identify, prevent and get rid of this pest?

Onion Fly: How to identify, prevent and get rid of this pest?

One of the most common onion pests, Onion Fly attacks onions, spring onions, shallots, garlic, and leeks. Do you want to know how to identify, prevent and control Onion Anthracnose effectively? This article, Garden How will help you gain a lot of useful information about this disease. 

The characters of Onion Fly

The characters of Onion Fly
The life cycle of an Onion Fly.

Eggs: are white and long and are arranged in groups on the stem, leaves, and tubers of the host plant and near the ground, in the soil crevices. 

Larva: Young caterpillars are called maggots. They are about 2mm long, and white in color, the front part is slightly yellow, and the inner intestine is clearly visible. Also, the life span of maggots is about 3-4 days. 

Yellow-brown pupa, about 1.5 mm long, 0,7mm wide. The incubation period is from 6 to 9 days. The pupae are usually distributed at the end of the petiole or below the ground. 

Adults: Onion Flies are 3-5mm in size, with black legs, transparent wings, and brown compound eyes. 

How to identify Onion Fly?

When you grow Onion, you have to face this pest. The female lays long, white eggs near the base of the tree, in the crevices of the soil. Eggs hatch in 2-7 days. After hatching, the young caterpillar crawls up, crawls into the leaf sheath, and goes to the tube or sheath. Young caterpillars eat leaf sheaths and develop fully in 2-3 weeks, young caterpillars often focus on destroying tubers and leaf sheaths, 50 maggots can eat 1 large onion sheath, and larvae can hatch from many eggs from female flies.

The strong worms emerge from the sheath of the leaf and pupate in the soil. Transform into butterflies and begin a new generation after two to three weeks. Pests frequently target the onion and garlic sections right before harvest in the third generation.

In addition to hurting the onion and garlic, the caterpillars’ consumption of their soft parts makes it possible for bacteria and fungi to enter the tubers, leading to tuber rot, root rot, withering leaves, and dead trees. pests during storage and after harvest.

How to prevent and get rid of Onion Maggot?

Traditional measures

To prevent Onion fly, you should clean the field, plow, dry the soil in the sun, and clean weeds, especially broad-leaved weeds (sub-hosts of flies) about 1 month before sowing.

  • Rotating crops with other crops, especially wet rice.
  • Cut off the leaves that are burrowed by flies to reduce the source of worms, especially the old leaves.
  • Use yellow sticky traps to trap adult flies.

Chemical measures

Use drugs with deep penetration and internal absorption such as Bulldock 0.25 EC; Trigard 75WP; Vertimec 1.8EC; Netoxin 18SL, and Sairifos 585 EC for spraying.

Using Trigard 75WP
Using Trigard 75WP to control Onion fly.


There is no need to spray during an investigation if the natural enemy rate is greater than 50%. Use the medication only when there are more than 7 flies per leaf after the garlic has grown.

Besides, you can control Onion Maggot by using biological pesticides or homemade pesticides from chili, garlic, onion…

Instructions for mixing homemade pesticides: Prepare 1kg of hot peppers, 1kg of garlic, 0.5kg of onions, 2.5 liters of dishwashing liquid, and 1 liter of water. Grind the whole amount of chili, garlic, and onion in a blender or pound it in a mortar, mix well with dishwashing liquid and filtered water, let it settle for 24 hours, filter out the inner part, and add water to make 1 spray bottle (16) liter).

Final Thoughts 

Onion fly is a highly localized pest and crop rotation may be an effective way of reducing the risk. So, Garden How gave you all of the useful information about How to identify, prevent, and get rid of Onion Fly. We hope this knowledge can assist you a lot in growing and caring for your Onion garden. Visit gardenhow.net to learn more about flowers and vegetables. Thank you for taking the time to read this!

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How to identify, prevent and control Onion Anthracnose?
How to grow Green Onions?

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