Leaf miner
Larvae feeding between the two surfaces of a leaf, leaving a pale winding tunnel or a dried blotch with the leaf surface still intact above and below it. That intact surface is the whole identification: a mine is not a hole, and anything that has removed leaf tissue entirely is a chewing pest instead.
Caused by: Larvae of various flies, moths and sawflies · also called leaf mining fly
What brings it on
Widespread outdoors in summer. Damage is usually cosmetic on an established plant and matters most on leaf crops, where the mined leaf is the part being eaten.
source
Horticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
Usually seen: May, June, July, August, September
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Pick off and destroy mined leaves as they appear, which removes the larvae before they mature.
source
Sourced guidancemoderate confidence
- Royal Horticultural Society: Leaf miners
Checked 2026-08-13
Dealing with it once it is there
- Tolerate it on ornamentals. The plant loses a small amount of leaf area and nothing else, and control measures are disproportionate to the damage.
source
Sourced guidancemoderate confidence
- Royal Horticultural Society: Leaf miners
Checked 2026-08-13
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.