Whiteflies

Also known as: Silverleaf whitefly, greenhouse whitefly

Identification

Tiny white-winged insects (1-2mm) that fly up in clouds when foliage is disturbed. Found on leaf undersides. Nymphs are flat, oval, translucent scales.

Damage

Sucking — feed on phloem, cause yellowing, honeydew/sooty mold, transmit geminiviruses

Best Organic Solutions (Ranked)

Solutions ranked by reliability tier — start with Tier A options.

Insecticidal Soap Tier A

Repeat applications needed — nymphs on undersides

Neem Oil Tier A

IGR disrupts nymph development

Horticultural Oil Tier A

Suffocates nymphs and eggs

Beauveria bassiana Tier B

Excellent in greenhouse environments

Biological Controls

Encarsia formosa (parasitic wasp), Delphastus catalinae (predatory beetle), green lacewing larvae

Prevention

Yellow sticky traps for monitoring. Screen greenhouse vents. Remove heavily infested leaves. Avoid over-fertilization.

Common Mistake

Only spraying the top of leaves — whitefly nymphs live exclusively on leaf undersides.