Two common indoor options are ready-to-use liquid lure traps and plug-in light traps that capture flies on adhesive refill cartridges.

Plug-in light traps use UV or blue light to lure flying insects, then trap them on an internal adhesive cartridge or sticky backing.

Many users report seeing catches within hours to a few days; some products advertise a first catch within 24 hours.

Ready-to-use liquid traps often contain a food-based, non-toxic lure that lasts about 30 days. Plug-in light traps use adhesive cartridges that you replace when full—typically about once a month for best performance.

Many plug-in devices are electric (plug-in, no batteries). Other traps are passive ready-to-use liquid or lure-based units that don’t require electricity.

Place traps where you see flying insects and near food sources like fruit bowls, trash cans, and houseplants. For plug-in light traps, use an outlet close to insect activity, avoid competing light (windows), position the unit upright, and leave it on continuously for best results.

Some products are marketed as people- and pet-friendly when used as directed, but labels generally warn to keep units and refills out of reach of children and animals, avoid eye contact, and have an adult handle refills or device maintenance.