Moth traps

This is not intended to be a complete guide to moth trapping, so we would be very happy if you could share your own knowledge and experience.

Guides

The NHBS Guide to Moth Traps

Influence of moth trap design and light source on moth capture rates

Classical Moth Trapping

Classical moth traps are among the most widely used and historically important tools in nocturnal Lepidoptera research. Long before the development of automated video tracking, harmonic radar, or telemetry-based approaches, these traps enabled entomologists to systematically sample moth communities and build the long-term datasets that still underpin our understanding of moth diversity, phenology, and population change.

This page provides an overview of the most common classical moth trap designs, their operating principles, strengths, and limitations, with a focus on their relevance for modern ecological and behavioural research.

General principle

All classical moth traps exploit the strong attraction of many nocturnal moths to artificial light, particularly light rich in ultraviolet (UV) and blue wavelengths. A light source draws moths from the surrounding area, while the trap structure (funnels, baffles, or enclosed boxes) guides them into a collecting chamber.

Importantly, these traps are passive sampling devices. They do not actively pursue insects or impose directional cues, but rely on natural phototactic behaviour. As a result, they are especially valuable for standardized monitoring and comparative studies across sites and years.

Main classical trap designs

Robinson trap

The Robinson trap is often regarded as the reference design for quantitative moth monitoring. It consists of a large box with a wide funnel beneath a powerful light source, traditionally a mercury vapour lamp.

Characteristics

Very high catch efficiency
Captures a broad taxonomic range of species
Bulky and relatively heavy
High power consumption

Typical applications

National and regional monitoring schemes
Long-term population trend analyses
Species-rich habitats where maximum catch efficiency is required

Skinner trap

The Skinner trap is a more compact, box-shaped design using vertical baffles to deflect moths downward into the collecting chamber.

Characteristics

Portable and easy to deploy
Compatible with mercury vapour and actinic light sources
Slightly lower catch rates than Robinson traps

Typical applications

Multi-site surveys
Standardised monitoring across landscapes
Private and academic recording programmes

Heath trap

The Heath trap is a lightweight design commonly used with low-power actinic tubes. It is especially popular where portability and low energy consumption are priorities.

Characteristics

Low power requirements
Can be battery operated
Selective towards UV-sensitive species

Typical applications

Remote or power-limited field sites
Garden and small-scale monitoring
Comparative studies using standardized low-intensity light

Rigid moth trap (bucket or rigid-box trap)

Rigid moth traps are a simplified and durable variant of classical box traps. They are typically constructed from rigid plastic containers (such as buckets or purpose-built plastic boxes) fitted with internal vanes and a small light source. Because of their robustness and simplicity, they are widely used in standardized monitoring schemes and volunteer-based recording networks.

Characteristics

Mechanically robust and weather-resistant
Compact and easy to transport
Usually operated with low-power actinic or LED UV light sources
Lower catch efficiency than Robinson or Skinner traps

Typical applications

Long-term monitoring programmes
Citizen-science and volunteer networks
Repeated sampling at fixed sites

Light sources in classical traps

Mercury vapour lamps

Mercury vapour lamps were historically the dominant light source in classical moth trapping. They emit intense UV and visible light and attract a wide diversity of moth species.

Advantages

Very strong attraction
High species richness

Disadvantages

High heat output
Fragile bulbs
Increasing regulatory restrictions

Actinic fluorescent tubes

Actinic tubes emit cooler, narrower-spectrum UV-rich light and have become a common alternative.

Advantages

Lower heat and power consumption
Safer and easier to standardise
Suitable for long-term comparative monitoring

Disadvantages

Lower overall catch size compared to mercury vapour

UV LED light sources

UV light-emitting diodes (UV LEDs) represent a more recent development in moth trapping and are increasingly used in rigid traps, portable light traps, and automated monitoring devices. They typically emit light in narrow wavelength bands (commonly 365–405 nm), targeting the spectral sensitivity of many nocturnal moths.

Advantages

Very low power consumption
Minimal heat production
Long lifespan and mechanical robustness
Easily powered by batteries or solar systems
High reproducibility between units

Disadvantages

Narrow spectral output compared to mercury vapour or actinic lamps
Often attract fewer species overall
Species composition may differ substantially from traditional light sources

Low-cost and DIY alternatives

In recent years, a wide range of low-cost and do-it-yourself (DIY) moth traps have emerged, driven by advances in LEDs, microcontrollers, sensors, and affordable fabrication methods. DIY light traps typically combine a simple enclosure (plastic box, bucket, or funnel), a low-power UV LED or actinic light source, and basic internal vanes or baffles. Many designs can be assembled from readily available materials at minimal cost.

Dutch Butterfly Conservation design

Instructions and How to use

UKCEH design

Blogpost and Biological Recording Company webinar

Our design

More info here

Other classical methods

Sugar (bait) traps

Sugar traps, also known as bait traps, rely on olfactory rather than visual attraction. A fermenting mixture—traditionally based on sugar, molasses, beer, wine, or fruit—is applied to tree trunks, posts, or suspended ropes shortly before dusk. Nocturnal moths are attracted to the volatile compounds released during fermentation and settle to feed on the bait.

Recipe:

Butterfly conservation

our recipe which was successfully used to catch Red Underwings (Catocala nupta) and Clifden Nonpareil (Catocala fraxini) in Austria (Autumn 2025): mixture of 500 ml red wine, 500 g sugar, honey, cherry jam and 50 ml bitters

Characteristics

Do not rely on artificial light
Particularly effective for species weakly attracted to light
Allow direct observation and selective sampling

Typical applications

Sampling autumn-flying and late-season species
Surveys in light-sensitive or protected habitats
Complementary sampling alongside light traps

Limitations

Strong bias towards nectar- and sap-feeding species
Highly dependent on bait recipe, temperature, and humidity
Poor standardisation across studies

Cotton sheet and UV lamp traps (light sheets)

Light-sheet trapping combines a vertical cotton sheet (or white fabric) with an ultraviolet or mercury vapour lamp positioned in front of it. Moths attracted to the light settle on the illuminated surface, where they can be observed, photographed, identified, or temporarily collected.

We recommend using a LepiLED UV lamp, which is powered by a power bank and is effective at attracting a wide range of species (in Europe). US analog – Entoquip UV light or EntoCam beam

Additionally, it can be used in combination with a powerful searchlight (e.g. a 1000 W halogen lamp or a high-output LED) to attract high-flying migratory moths (Underwings in Europe and Bogong moths in Australia).

Characteristics

Highly interactive and non-destructive sampling method
Enables real-time observation of behaviour and activity patterns
Flexible setup adaptable to many habitats

Typical applications

Rapid biodiversity assessments
Behavioural observations at light
Photographic documentation and voucher selection

Limitations

Strongly observer-dependent
No enclosed collecting chamber (individuals may leave at any time)
Less suitable for quantitative abundance estimates