Trap Catch Threshold & Spray or Monitor

By the average catch per trap against the action threshold. Average per trap = total catch ÷ number of traps. If that average reaches or exceeds the threshold per trap, the tool says spray; if it is below, it says monitor. Averaging across traps smooths out a single hot trap and gives a fairer read of pest pressure.

One trap can sit in a hotspot or a dead zone, so a single count is noisy. Averaging several traps across the block gives a more reliable measure of the moth flight. The tool divides the total catch by the number of traps so your decision rests on field-wide pressure, not one lucky or unlucky trap.

It is the average catch at which spraying is justified — published for many pests as moths per trap per period. Below it, the expected damage does not pay for control; at or above it, treatment protects more value than it costs. Use the threshold from guidance for your specific pest, crop and trap type.

Spraying below threshold wastes product, money and beneficial insects on a population unlikely to cause economic loss, and adds resistance pressure. The threshold marks where damage risk crosses the cost of control, so acting at or above it targets sprays where they actually pay. Below it, monitoring is the cheaper, smarter choice.

It means keep the traps running and recount on schedule rather than spraying now. Catches build through a flight, so a below-threshold average today can cross the line in a few days. Monitoring catches that rise early and lets you time a spray for the moment it becomes worthwhile.

It works with any traps reported as a count per trap — pheromone traps for moths are the classic case, but light, sticky or bait traps fit the same maths. The key is that the threshold you enter matches the trap type, lure and pest the threshold was set for, since catch rates differ between trap designs.

Typically once or twice a week through the pest's flight period, replacing lures and sticky liners on schedule so catch rates stay comparable. Consistent timing and maintenance keep the averages meaningful; a clogged or expired trap under-counts and can hide a real outbreak.

The trap threshold itself is usually fixed by guidance, but crop susceptibility and weather affect how a given catch translates to damage — a vulnerable growth stage or warm, fast-developing conditions raise the stakes. Use the calculator for the catch decision and factor crop stage and forecast into the final call.

They're solid working figures for a spray decision. Trap catches vary with weather, trap placement and lure age, and thresholds are guidance rather than hard cut-offs. Treat the result as a strong signal, confirm with scouting for actual damage, and follow local recommendations before spraying.