Insect

Mayfly

Hexagenia limbata

Low Risk

Biology

Hexagenia limbata is a large pale yellow mayfly with upright transparent wings and two or three long tail filaments. Nymphs burrow in lake and river sediment for one to two years; adults live one to two days and do not feed.

Behaviour

Synchronized emergences produce enormous nightly swarms around lakeside lighting from late spring through summer. Adults are harmless, cannot bite, and die within hours of mating.

Habits

Drifts of dead mayflies pile against buildings, block vents and gutters, create slippery road surfaces, and generate a fishy odor. They are a strong indicator of clean surface water nearby.

Control methods

1Turn off or shield exterior lights during emergence nights
2Use warm amber LEDs that attract far fewer insects
3Sweep and compost drifts promptly to limit odor
4Screen vents, gutters, and intake louvers
5Close doors and windows during peak evening flights
6Pressure-wash siding after large emergences

Tailored to Mayfly

IPM Procedure Checklist

View full procedure

Step 1

Inspection

Inspect harborage near food, water and warmth
Check cracks, voids and appliance interiors
Place sticky monitors at suspected hot-spots

Step 2

Identification

Confirm Mayfly (Hexagenia limbata) — not a look-alike
Note life stage and risk level: Low
Capture clear photos and samples for the record

Step 3

Action Thresholds

Tolerate low-level activity outside sensitive zones
Act if activity moves indoors or near food
Review threshold seasonally with the client

Step 4

Prevention

Seal cracks, plumbing penetrations and wall voids
Eliminate moisture sources and standing water
Improve sanitation: sealed food storage, grease removal

Step 5

Control Methods

Turn off or shield exterior lights during emergence nights
Use warm amber LEDs that attract far fewer insects
Sweep and compost drifts promptly to limit odor
Screen vents, gutters, and intake louvers

Step 6

Monitoring & Evaluation

Service monitors on schedule and trend captures
Re-inspect for Mayfly activity at follow-up
Adjust tactics based on data; report findings to client