The most effective butterfly trap you can build at home is a bait trap, sometimes called a Van Someren-Rydon trap. It uses a simple cylinder of mesh netting, open at the bottom, suspended over a platform holding fermented fruit bait. Butterflies fly up from below to feed, then instinctively fly upward to escape and become contained in the mesh cylinder. The whole thing can be assembled in an afternoon with inexpensive materials.
How a Bait Trap Works
The standard design is a cylinder of fine mesh or netting held open by wire hoops, closed at the top and open at the bottom. The cylinder hangs from a tree branch or hook, and a flat base (a piece of plywood, a plastic plate, or even a paper plate) sits at the bottom opening. Bait goes on that base. Butterflies land on the platform to feed, and when startled or finished, they fly upward into the mesh cylinder rather than back down through the opening.
Adding an inverted cone inside the cylinder dramatically improves retention. The cone funnels upward with a narrow opening at its tip, about 20 centimeters (8 inches) wide. Butterflies pass through the cone’s opening easily on their way up but struggle to find it again when trying to leave. Think of it like a lobster trap: easy in, hard out.
Materials You’ll Need
For a basic bait trap, gather the following:
- Fine mesh netting or tulle fabric: enough to form a cylinder roughly 30 centimeters wide and 60 to 90 centimeters tall. White or light-colored mesh works best since it’s less visible to approaching butterflies. Wedding tulle from a fabric store is cheap and effective.
- Wire hoops: two or three circles of stiff wire (coat hangers work) to hold the cylinder open. One for the top, one for the bottom opening.
- A flat base: a piece of plywood, a plastic plate, or a shallow dish about 30 centimeters across.
- Cord or rope: to hang the trap from a branch.
- Optional cone insert: a piece of the same mesh fabric sewn or shaped into a funnel, narrow end pointing up, mounted inside the cylinder about one-third of the way from the bottom.
If you want something sturdier for repeated use, corrosion-resistant steel wire mesh (8-by-8 mesh with a wire diameter around 0.032 inches) makes a rigid, durable cylinder that holds its shape in wind and rain. You can cut a sheet roughly 60 by 30 inches, roll it into a cylinder, and secure the seam with baling wire.
Building the Trap Step by Step
Start by forming your wire hoops. Bend two lengths of stiff wire into circles matching the diameter you want for your cylinder, roughly 25 to 30 centimeters across. If you’re using coat hangers, unwind them, shape the circles, and twist the ends together.
Cut your mesh netting into a rectangle tall enough for the cylinder (60 to 90 centimeters works well for most species). Wrap it around the two hoops, one at the top and one at the bottom, and secure the netting to the wire with zip ties, thread, or small clips. Sew or tie the netting closed at the top so nothing escapes upward. Leave the bottom fully open.
For the cone insert, cut a circle of mesh about 30 centimeters across, then cut a slit from edge to center and overlap the edges to form a funnel shape. The narrow opening at the top of the funnel should be about 5 to 8 centimeters wide. Attach this cone inside the cylinder with its narrow end pointing up, positioned roughly one-third of the way from the bottom. Sew or zip-tie the cone’s outer edge to the cylinder walls.
Attach three or four lengths of cord to the top hoop, gather them above the trap, and tie them to a single hanging line. Your base plate attaches at the bottom. You can rest it on the lower hoop or suspend it with short cords so it sits level.
Making Fermented Fruit Bait
Butterflies are strongly attracted to fermenting fruit. The sugars breaking down produce alcohols and esters that they can detect from a surprising distance. A well-made bait will keep working for weeks.
A proven recipe from Loyola University calls for 8 to 10 very ripe bananas (the browner the better), 2 cups of white sugar, 2 cans of regular beer (not light beer, which doesn’t ferment as well for this purpose), and enough water to cover everything in a one-gallon jar. Mash the fruit, mix everything together, and set the lid on loosely. Do not tighten it, because the fermentation gases can build enough pressure to crack the jar. Leave it outside for two to three days in warm weather, and you’ll have a pungent, effective bait.
Other fruits work well too. Peaches, plums, cantaloupe, and apples can be used alone or in combination. Avoid adding fibrous peels like banana skins or cantaloupe rinds, as they don’t break down cleanly. The finished bait smells terrible to humans but is irresistible to many butterfly species.
Spoon a few tablespoons of bait onto the trap’s base plate. Replace it every two to three days, or whenever it dries out or gets washed away by rain.
Where and When to Set Your Trap
Placement matters more than most people expect. Hang the trap at roughly 1 to 1.5 meters off the ground in a spot that gets partial sun. Full shade reduces butterfly activity nearby, but intense direct sun can dry out your bait quickly and make the trap area too hot. Forest edges, garden borders, and clearings near flowering plants are ideal spots. If you’re in a wooded area, a horizontal trap design placed directly on the forest floor can also work, since some species feed primarily at ground level on fallen fruit.
Timing your trap around peak activity hours makes a big difference. Research in tropical environments found that 96% of butterfly species forage most actively around solar noon, with 63% of all feeding observations occurring between 10 a.m. and 2 p.m. Sunlight appears to be the primary cue that triggers foraging. On very hot days, activity may dip at midday as temperatures exceed what butterflies can tolerate, pushing peak feeding to mid-morning or mid-afternoon instead. Set your trap out early in the morning so the bait scent has time to spread before the active window begins.
Seasonally, late spring through early fall covers the flight period for most temperate species. In tropical regions, trapping can happen year-round.
Keeping the Trap Clean
Fermented bait in warm weather is a recipe for mold. Left unchecked, mold growth can make the trap repellent rather than attractive and can also harm any butterflies you catch. Clean the base plate every time you refresh the bait. A rinse with a diluted bleach solution (about half a teaspoon of household bleach per cup of water) kills mold spores effectively. Let the bleach sit on the surface for 15 to 20 minutes, then rinse thoroughly with water before adding fresh bait. For a quicker clean between uses, wiping down with a 70% rubbing alcohol solution works well.
Good airflow around the trap helps prevent mold from taking hold in the first place. Avoid placing your trap in stagnant, humid pockets where air doesn’t circulate.
Handling and Releasing Butterflies Safely
Butterfly wings are covered in tiny scales that rub off easily with handling. If you’re trapping for observation, photography, or a school project, minimize the time butterflies spend inside the trap and avoid touching their wings directly.
Best practice guidelines from conservation organizations recommend keeping your catch in cool, shady conditions and releasing at dusk, when butterflies naturally settle and are less likely to be picked off by predators in the open. If you can’t wait until dusk, release them into tall grass or other ground cover rather than on exposed surfaces like lawns or pavement. Release near the capture site but not right next to the trap, so they don’t immediately fly back in.
Never use chemical anesthetics on trapped butterflies. These substances cause lasting harm. If a butterfly seems stressed or is beating its wings against the mesh repeatedly, release it promptly. Egg-tray material or crumpled paper towels placed inside the trap gives butterflies something to grip and rest on, which reduces wing damage from fluttering against bare mesh.
If you’re not conducting a formal scientific study, consider whether you need to trap at all. For identifying species in your garden, close-up photography near flowering plants or bait stations (without a trap enclosure) often gets the job done without confining anything.