These coils manufactured in Thailand contain three natural ingredients traditionally used in this country to keep those biting bugs at bay: eucalyptus, citronella and turmeric.

The first step is to mix them with certain non-active natural ingredients which form the coil.

Coconut shell powder, sawdust, tapioca starch and joss powder, an adhesive made from the bark and leaves of the Litsea glutinosa tree.

Then they add the coil's only chemical active ingredient: meperfluthrin.

Its vapors are toxic to mosquitoes' nervous systems, yet harmless to humans at low doses.

A conveyor belt transports it to an extruder, which squeezes the paste through a slot shaped die, producing sheets approximately 5 mm thick.

A stamping machine then punches out 7 coils per sheet.

The leftover paste travels back to the extruder to be reformed into fresh sheets.

After 5.5 hours, the coils come out of the drying chamber hard and sturdy.

After conducting another visual inspection, workers transfer the dried coils to the automated packing line.

The machine's first station stacks the coils and piles of five.

Workers place a metal coil stand on each stack.

Then the machine's next station packages each stack in clear plastic film.

The package holds the five coils tightly together so they don't rattle against each other and get damaged.

It also prevents the scent from dissipating before use.

At the next station, a high speed robotic arm grabs and opens the retail boxes aligning them opposite the arriving packages of coils.

The machine inserts the package of coils into each box, then closes the box.

Provided they're kept sealed in their plastic package and stored away from moisture, the active ingredients remain effective for at least 10 years.