How to Identify Moth Species in the UK
Britain is home to approximately 2,500 species of moth — vastly outnumbering the 59 resident butterfly species. They range from the spectacular (the elephant hawk-moth, with its pink and green livery) to the minute (micro-moths with wingspans of just 3 mm). Moth identification can seem daunting, but with systematic observation and good resources, it is a deeply rewarding pursuit accessible to anyone.
Moths vs. Butterflies
Moths and butterflies both belong to the order Lepidoptera. The distinction between them is largely traditional rather than taxonomic — there is no single feature that separates all moths from all butterflies. However, some general guidelines apply:
| Feature | Moths (general) | Butterflies (general) |
|---|---|---|
| Antennae | Varied: feathery, thread-like, or hooked | Clubbed (swollen at the tip) |
| Activity | Mostly nocturnal (many exceptions) | Diurnal (day-flying) |
| Resting posture | Wings flat or tent-like over body | Wings held vertically above body |
| Body shape | Often stout and furry | Usually slender |
| Pupation | Often in a silk cocoon or underground | Chrysalis (usually exposed, no cocoon) |
| Diversity (UK) | ~2,500 species | ~59 resident species |
Key Identification Features
When identifying a moth, focus on these key characteristics:
Step-by-Step Moth Identification
- Size: Measure or estimate the wingspan. Is it a large macro-moth (wingspan > 20 mm) or a small micro-moth (< 20 mm)?
- Wing shape: Broad and rounded? Narrow and pointed? Angular or scalloped edges?
- Wing pattern and colour: Note the ground colour and any cross-lines, spots, bands, or distinctive markings. Pay particular attention to the kidney mark (reniform stigma) and oval mark (orbicular stigma) found on many noctuid moths.
- Resting posture: Does it rest with wings flat, tent-like, rolled, or upright?
- Body features: Note the body colour, fur, and antenna type (feathery = often male; thread-like = often female).
- Time of year: Many species fly only during specific months. A pink-barred sallow in October is very different from a lime hawk-moth in May.
- Habitat: Woodland, garden, heathland, or coastal? Some species are strongly associated with particular habitats.
- Behaviour: Does it come to light? Does it hover at flowers (hawk-moths)? Does it fly during the day?
Common UK Macro-Moths
Ten Moth Species Every Beginner Should Know
- Elephant hawk-moth (Deilephila elpenor): Large; stunning pink and green. Flies May–July. Caterpillar has eye-spots and feeds on willowherb.
- Poplar hawk-moth (Laothoe populi): Grey-brown with a distinctive resting posture (hindwings project forward of forewings). Common May–August.
- Peppered moth (Biston betularia): Famous for industrial melanism. Pale with dark speckles, or entirely dark in polluted areas.
- Garden tiger (Arctia caja): Boldly patterned — chocolate and white forewings, orange and black hindwings. Declining in the UK.
- Large yellow underwing (Noctua pronuba): One of the commonest moths at light traps. Brown forewings; bright yellow-orange hindwings flashed when disturbed.
- Silver Y (Autographa gamma): Immigrant moth with a distinctive Y-shaped silver mark on each forewing. Arrives from southern Europe in variable numbers each year.
- Buff ermine (Spilosoma lutea): Cream-coloured with scattered dark spots. Common in gardens, May–July.
- Hummingbird hawk-moth (Macroglossum stellatarum): Day-flying; hovers at flowers like a hummingbird. A summer immigrant, increasingly common.
- Brimstone moth (Opisthograptis luteolata): Bright yellow with chestnut blotches. Common in gardens and hedgerows April–October.
- Angle shades (Phlogophora meticulosa): Olive and pink; distinctive crumpled wing posture mimics a dead leaf. Common almost year-round.
Moth Trapping
The most effective way to see and identify moths is to use a light trap. Moths are attracted to ultraviolet light, and a properly operated moth trap can record dozens to hundreds of species over a single night.
Did you know? No licence is needed to operate a moth trap in the UK, and the moths are not harmed. They rest inside the trap overnight, are identified and counted in the morning, and then released into nearby cover. Moth trapping is one of the most accessible and rewarding forms of wildlife recording.
Common trap types include:
- Robinson trap: A large, bucket-like trap with a mercury vapour or actinic UV bulb. The most effective design, but bulky and requires mains power.
- Skinner trap: A flat, folding trap with angled Perspex sheets funnelling moths into a box. Portable and effective.
- Heath trap: A small, lightweight trap ideal for fieldwork and remote sites. Uses an actinic (low-power UV) bulb and can run from a battery.
Recording and Resources
The UK has an outstanding network of moth recording schemes. Key resources include:
- The Concise Guide to the Moths of Great Britain and Ireland by Townsend & Waring — the standard field guide.
- iRecord and National Moth Recording Scheme: Online platforms for submitting moth records to contribute to conservation science.
- Moth Trap UK Facebook group and Twitter/X #MothsMatter: Active communities for identification help.
- Butterfly Conservation: Runs the National Moth Night and provides regional moth recording guidance.
Key Takeaway
Moth identification in the UK is a rewarding and accessible hobby supported by excellent field guides, recording schemes, and online communities. With approximately 2,500 species to discover — many of them strikingly beautiful — moths offer a lifetime of exploration. A simple light trap in your garden can reveal a hidden world of nocturnal diversity that rivals anything seen during the day.