Thrips, Fungus Gnats & Aphids
The flying and root-zone pests — silvery-streak thrips, damping-off fungus gnats, honeydew aphids and the deficiency-mimicking root aphid — with card thresholds, the dry-back lever, and the predators for each.
8 min read
Thrips, fungus gnats, and aphids are the pests your sticky cards were designed to catch. Unlike mites, most of these you can see — the challenge is catching them early and choosing between a foliar predator, a soil predator, or a nematode drench depending on where the life stage lives.
| Pest | Signature | Location | Monitoring / threshold | Biocontrol |
|---|---|---|---|---|
| Thrips (Western flower) | Silvery streaks + tiny black frass dots; dull, deformed new growth | Upper surface, new growth, into flowers | Blue cards ~1/100–200 ft²; ~5–10 adults/card/week rising (ornamental ref) | swirskii + cucumeris (larvae); Orius (adults); S. feltiae drench (pupae) |
| Fungus gnats | 2–3 mm dark flies; larvae cause damping-off, wilt despite moist media | Top 2–3 cm wet media; larvae at roots | Yellow cards at media surface; ~20 adults/card/week (ornamental ref); act low in prop | S. feltiae, S. scimitus, Bti; primary lever = let media DRY BACK |
| Aphids | Clusters + honeydew → black sooty mold; curled tips; white cast skins | Undersides, new shoots, buds | Act on first colony | Aphidius colemani/ervi, Aphidoletes; Beauveria bassiana |
| Root aphids | Deficiency-look that won't correct + droop; waxy white/blue-white aphids on roots | Root zone | Inspect roots on first suspicion | S. scimitus + S. feltiae drench; Beauveria; sanitation |
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