Our pop-up butterfly bait trap easily fits into backpacks for field trips because it is lightweight (310 grams) and extremely small (21 cm diameter by 5 cm thick) after folded.
Of 96 x 26 mesh polyester netting, this butterfly bait trap has a full-length (about 90 cm) zippered side opening for removal of captured butterflies. The trap is held open by foldable rings (38 cm in diameter) at top and bottom of the black cylinder. Inside are a white top and a white funnel with a 10 cm diameter opening. A removable bait tray (20 cm in diameter, included) hangs by plastic hooks from three drawstrings beneath the cylinder. To hook tray to cylinder, pass the hook through the hole in the tray so the open part of the hook is outside the tray.
An 8 cm long "skirt" is sewn to the bottom. You can either fold up this skirt or use the cord lock attached to each drawstring to adjust the gap between bait tray and bottom entrance.
For a larger landing platform, simply attach cardboard or hard plastic sheeting (not provided) to bottom of the tray.