Celery Leaf Miner

Symptoms by part

Causes

• Adult flies laying eggs on the underside of leaves.
• Warm temperatures that speed up the life cycle of the larvae.
• Lack of physical barriers like row covers that allow flies to reach the foliage.

Could be confused with

• Septoria leaf spot · Leaf spot creates distinct, circular brown lesions with tiny black dots in the center, rather than winding tunnels.
• Nutrient deficiency · Deficiencies usually cause uniform yellowing or discoloration across the entire leaf, not specific tunnel patterns.

Treatment

1. 1. Pinch off and destroy any leaves showing visible tunnels as soon as you spot them to remove the larvae inside.
2. 2. Use a fine mesh row cover over your plants to block adult flies from landing and laying eggs.
3. 3. Apply spinosad to the foliage if the infestation is widespread, follow the label.

Without chemicals

• Hand pick and destroy infested leaves.
• Install fine mesh row covers early in the season to prevent egg laying.
• Remove weeds like sow thistle or hogweed nearby that can host the flies.

Chemical options

• Spinosad, apply to the foliage when larvae are active, follow the label.

Preventing it

• Rotate your crops so celery is not planted in the same spot every year.
• Keep the area free of weeds that serve as alternative hosts for the flies.
• Use floating row covers from the time of planting to protect young leaves.

When to act

Act immediately when you see the first white trails on the leaves to prevent the larvae from maturing. If the infestation covers more than half of the plant's foliage, it is best to remove the plant entirely to stop the spread to neighbors.

Questions people ask

Are the leaves safe to eat if they have tunnels?

Yes, the tunnels are cosmetic and the plant remains edible, though you should trim away the affected parts before cooking.

Do these miners kill the plant?

They rarely kill a plant outright, but they can significantly stunt growth and reduce the quality of your harvest if left untreated.

Plants it affects

• Celery