Planning reference

Spider Mites vs Leaf Miners

Compare spider mites and leaf miners by stippling, webbing, moving dots, winding mines, blotches, internal larvae, edible leaves, row covers, and plant stress.

What each leaf-damage clue can mean

Spider mites
Spider mites are tiny arachnids that usually feed on leaf undersides. They are easiest to confirm with a hand lens or by tapping leaves over white paper and watching for tiny moving dots.
Leaf miners
Leaf miners are fly larvae that feed between the upper and lower leaf surface, leaving winding trails, blotches, opaque tunnels, frass lines, or larvae inside the leaf instead of open surface holes.
Stippling, webbing, and tiny moving dots
Fine pale stippling, bronzing, yellowing, cast skins, underside webbing, and tiny moving specks point toward spider mites, especially on hot, dusty, or water-stressed plants.
Winding trails and blotches inside leaves
Pale serpentine mines, expanding blotches, cloudy tunnels, brown mines, or larvae visible between leaf layers point toward leaf miners, especially on spinach, chard, beets, lettuce, beans, peas, tomato, pepper, potato, cucumber, squash, melon, onion, or other edible leaves.
Surface feeding, internal mines, and edible leaves
Mite injury stays on the surface and can worsen with heat, dust, drought stress, or predator loss. Leafminer injury is inside the leaf and matters most when the harvested crop part is the damaged leaf.

Decision workflow

Confirm where the injury sits
Do not treat every pale, speckled, tunneled, or bronzed leaf as the same pest problem; check whether damage is scraped or stippled on the surface or inside the leaf, tap leaves over white paper, look for webbing, tiny moving dots, cast skins, winding mines, blotches, larvae, row-cover history, edible-leaf harvest plans, heat, dust, water stress, recent sprays, and natural enemies before treating spider mites or leaf miners.
Tap, flip, and split leaves
Flip stippled leaves and tap them over white paper for mites. Hold mined leaves to light or split a fresh mine to look for a larva, frass line, or pocket between the leaf surfaces.
Separate surface injury from internal injury
Spider mite stippling removes cell contents from the surface and can create bronzing or webbing. Leafminer larvae feed inside the leaf, so the trail or blotch stays between leaf layers instead of rubbing off or opening into a hole.
Value the edible leaf
A few mines on beet roots or tomato leaves may not justify the same response as mines on spinach, chard, lettuce, or other leaves harvested directly. Mite stippling on stressed fruiting crops may call for water, dust, and predator-preservation checks first.
Time covers and stress fixes
Use covers before leafminer adults arrive and remove or manage them around heat and pollination. Covers do not fix spider mite pressure, and sealed hot covers can make stressed plants worse.

Use these paths

Source basis