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Would you like to find out what small creatures are crawling around your garden? Follow our instructions on how to set up a simple pitfall trap.
A pitfall trap is a simple device used to catch small animals - particularly insects and other invertebrates - that spend most of their time on the ground.
In its most basic form, it consists of a container buried so that its top is level with the surface of the ground. Any creatures that wander nearby may fall in. Any that can't escape by climbing, jumping or flying out will remain trapped until you release them.
You will need:
1. Choose a location for your trap on flat ground near vegetation.
2. Use a trowel to dig a small hole.
3. Place a clean yoghurt pot in the hole. Fill in any empty space around the pot with soil. Make sure that the top of the pot is level with the ground, or you won't catch anything.
4. Leave your trap overnight. If you prefer to leave it during the day, check it at least every few hours.
5. Empty the trap into a tray to see what creatures wandered in. Use ID guides (books, online resources or apps) to help you identify what kind of invertebrates they are.
6. Record your findings: make a note of what you caught, the date and location. You could also draw the creatures or take photographs.
7. Carefully release the creatures, returning them to a safe, sheltered place.
8. Return the area back to how you found it.
Museum scientist Sam Thomas regularly sets up pitfall traps in the Museum's gardens as part of biodiversity monitoring of the area. He has these tips for anyone who wants to try setting up their own pitfall traps:
Pitfall traps catch ground-dwelling invertebrates, including insects.
The main creatures that are likely to fall into your trap are beetles, woodlice, millipedes, centipedes, earwigs, springtails and spiders that hunt on the ground. You'll possibly also encounter worms, slugs and snails.
Here are some of the more common UK invertebrates you might catch:
This millipede is up to 2cm long and curls into a small ball if threatened. Two pairs of legs per segment distinguish it from the pill woodlouse, which only has one pair per segment.
This garden regular hunts around compost heaps and under stones. When fully grown it has 15 pairs of legs along its broad, brown body and is up to 3cm long. It has long antennae and hind legs
Like other woodlice, it has seven pairs of legs and an oval-shaped body divided into multiple segments. It is typically grey or brown with pale, irregular patches. Adults are glossy, but juveniles have a rough texture.
This woodlouse is usually grey, but some can be more orange, brown or mottled. Tiny bumps on the exoskeleton give it a rough appearance.
It can be distinguished from the pill millipede by the number of legs per segment and its three small plates at the tail end.
These very abundant, tiny invertebrates feed on decaying vegetation. They are less than 6mm long. They have a tail-like appendage that they use to jump.
Most of these tiny spiders are less than 5mm long. They build horizontal sheet webs to catch their prey, sometimes on low vegetation or depressions in the soil.
These spiders hunt their prey on the ground. They grow to about 8mm long and are quite hairy, with a brownish body and brown, grey and black markings. There are several species that are quite hard to distinguish.
Woodlice are the main prey of this spider. Its fangs are strong enough to pierce a woodlouse's hard exoskeleton, so it's also capable of giving people a painful, but harmless, bite. The similar D. erythrina is unlikely to be found in urban environments.
Earwigs grow to about 13mm and have a long, slim body, but their most recognisable feature is their pincers. Male earwigs have curved pincers, while females have straight ones.
Any beetles in the trap are most likely to be ground beetles (Carabidae family) or rove beetles (Staphylinidae family). There are over 350 ground beetle species in the UK, ranging in size from two millimetres to three centimetres. Rove beetles are the most diverse UK beetle family, with more than 1,000 species recorded here. We've highlighted a few common ones below, but it is difficult to identify most to species level.
Ladybirds (Coccinellidae family) are unlikely to get caught in your trap, as they're strong fliers and tend to spend their time on plants feeding on aphids. But harlequin ladybird larvae are very common and you may well see some of these.
With the exception of having six legs, the larvae look nothing like the adults they grow into. Their spiky bodies are orange and black, and up to 1cm long.
This common garden species grows up to 3cm long and has a metallic purple sheen. Carabus problematicus looks similar but its fused wing cases have distinct ridges and dimples.
In sunlight, this centimetre-long beetle has a handsome metallic blue body. It is a very fast runner, often found among overgrown vegetation in gardens.
There are many similar Amara beetles. They are generally less than a centimetre long, with a shiny bronze or black bullet-shaped body.
At nearly 3cm long, this is the UK's largest rove beetle. It is often found in gardens under logs and stones, or among leaf litter. If it feels threatened it rears up its tail. Watch out for its painful but harmless bite.
If you don't catch much on your first try, don't give up. Try placing your pitfall trap in a different area near more vegetation. You could compare what and how much you catch in different locations.
You could also try adding bait to your trap. A banana may entice some creatures. Be careful not to leave the banana in the trap too long, though - you don't want to return to find things encased in decaying banana goo. Bear in mind you're likely to have a stream of ants moving back and forth to the banana.
Sam also has another suggestion:
'If you have access to fresh animal dung, such as guinea pig or rabbit pellets, you could put some of these in your pitfall trap.
'You might catch dung beetles, even in urban areas. These are quite different from the tropical species that roll dung balls. UK species instead live in the poo or bury it below ground.'
More than 50 beetle species in the UK depend on dung.
The iNaturalist app both helps to identify wildlife you photograph and contributes your findings to international scientific databases.
If you're in the UK and have trouble identifying the insects you find, you can also get in touch with the Museum's Identification and Advisory Service.
Buglife's key to UK land invertebrates PDF (584KB)
NatureSpot has helpful image galleries for many species of invertebrates observed in Leicestershire and Rutland.
The Field Studies Council sells a variety of invertebrate identification charts.
If you would like your wildlife findings to be useful for science and conservation, you can upload your observations and photos to the Biological Records Centre's iRecord. Your findings will then be available to national recording schemes.
Discover how to record the wildlife in your urban environment.