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Pest, Disease & Weed Timing CalendarsPheromone Trap Timing
Pheromone traps tell you when adult moths arrive, and that date helps you decide when to start scouting for eggs and larvae.
Key points
- Pheromone traps monitor adult flight, they do not control pests.
- Set them before expected flight and check on a regular schedule.
- Use your state's biofix definition to start degree-day counting.
- Combine trap data with field scouting before making decisions.
- Keep traps and lures fresh, because old lures give misleading counts.
What does a pheromone trap actually tell you?
A pheromone trap uses a scent lure that attracts males of a particular insect, usually a moth, into a sticky or funnel trap. It does not control the pest. It shows when adults are flying and how their numbers change over time.
That information helps you time scouting, spray decisions where used and other actions. Extension programs publish trap protocols and thresholds for specific pests, which are the right references for action decisions.
Remember that trap catch measures flight, not damage. A busy trap week may still produce few eggs if weather is poor.
- Use the lure made for your target pest
- Hang traps at the height your protocol states
- Keep clean gloves for handling lures
- Note first catch date every year
When should you set traps out?
Set them before the expected start of adult flight. Extension pest alerts, degree-day accumulations and last year's records can help you pick the time. Putting traps out early costs little, while setting them late can miss the first flight.
For example, if your state extension newsletter says flight usually begins after a certain accumulated heat, set traps a bit before you reach that point in your location. Use local data for your pest.
If you are unsure of the time, ask a neighbor or your agent when they saw the first moths last year, then set traps a little earlier to be safe.
How often should you check them?
Check at least weekly, and more often during peak flight if advised. Record the date and count, then clear the trap. Keep a simple chart so you can see peaks and drops. Replace sticky liners when dirty or full, and replace lures on the schedule the manufacturer states.
Lures differ by species and brand, and mixing them in one place can confuse results. Store spares as directed and handle them with clean gloves to avoid contaminating them.
Keep a spare set of liners, lures and gloves in a labeled box so checking day goes quickly and nothing gets mixed up.
- Label each trap with location and date set
- Check on the same day each week
- Replace lures and liners as directed
- Keep different species' lures separate
What is a biofix and why does it matter?
A biofix is the date when consistent moth catches begin, as defined by the protocol for that pest. Many extension models start counting degree-days from this point to predict egg hatch and larval stages, which tells you when to scout or time any control.
Use the definition in your state's protocol. Different pests and programs define biofix in slightly different ways, and applying the wrong one gives the wrong timing.
Write the biofix date at the top of your log with the weather conditions. It helps you compare seasons.
Where should traps be placed?
Follow the recommended height and spacing for your pest and crop. Put traps in the crop or at the edge as advised, away from strong winds and heavy shade, and mark them so you can find them again. Use more than one trap per field where protocols call for it, since a single trap can mislead.
Avoid placing traps where sprays will drift onto them unless labels and protocols allow. Keep records of positions for the next season.
Replace damaged traps promptly. A missing or tipped trap leaves a gap in your record.
How do trap counts feed decisions?
A trap count is one input, not an answer. Combine it with field scouting for eggs, larvae or damage, crop stage and weather. Extension thresholds describe how counts relate to action in some pests, but they apply only where researchers have validated them.
If you use any pesticide, follow the label, pre-harvest interval and pollinator protections, and check your state's applicator licensing rules.
Never apply any product based on trap count alone. Verify with field scouting and the label.
What does a simple trap log include?
For each trap record the date, location, count, lure change date, weather notes and any scouting findings that week. After the season, add a one-line summary of what the data told you and what you did.
Over several years, this log becomes a local flight calendar. It is more accurate for your farm than any general dates.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.