My childhood summers were spent mostly outdoors, till very late at night. The Mediterranean nights are balmy, warm entities with inviting arms, when the nature is still buzzing in full force, the sky is pitch black but the stars can be clearly seen, and the energy from the sun-soaked bodies which have enjoyed their siesta in the early afternoon (unless us children rebelled by sneaking out of the room as soon as the elders slept to catch cicadas) take a long time to unwind and get ready for a good night's sleep. It was only natural that staying out so long produced its own pattern of rituals: backgammon-playing by the blue-tinged lights of the terraced porch watching the boats dock at the bay in the distance, chasing frogs by the small watering poodles in the yard, hanging fresh herbs from the fields upside down to dry, raiding the fridge for watermelon & feta cheese if bored and of course the "ceremony" of lighting incense coils for repelling mosquitos at sundown. Those tiny insects sure knew how to bite if left unattended, making us scratch and scratch our legs ad infinitum...or so it seemed.
We affectionally called that spiral (hey, we still do!) φιδάκι "fee-THA-ki", i.e. "little snake", due to its shape. These mosquito coils have their detractors who can't stand the smoky smell; they insist the product relies on a placebo effect ~one's mental perception of the insect bites is blunted by the fumes, as if smoking cannbis or something (come to think of it, the smell does have a cannabis note in there). And they have their ardent fans who love them just because of that particular smelly smoke they emit. You can count me among the latter...I just love it; does this come as any surprise?
Typically mosquito coils in this part of the world (and in Asia) are held at the center of a spiral, suspending it in the air, or wedged by two pieces of fireproof nettings to allow continuous smoldering. Burning begins at the outer end of the spiral, slowly progressing toward the centre, taking hours; a process that is as navel-gazingly, painfully slow as to render it almost a philosophical pastime.
Do not be fooled, the history of the mosquito coil is an old one, as befits these pastimes, clicking audibly like the amber on a lazy man's beads: Pyrethrum (Chrysanthemum cinerariaefolium) was used for centuries as an insecticide in Persia and Europe and the mosquito coil was developed around 1890s by a Japanese business man, Eiichiro Ueyama. The Japanese used to combine pyrethrum powder with sawdust and burn it in a brazier or incense burner. Initially, Ueyama created incense sticks mixed from starch powder, dried mandarin orange skin powder, and pyrethrum powder. It was his wife who had the idea of coiling the incense into a spiral so as to extend the duration of the mosquito-repellent smoke for maximum practicality and his company, Dainihon Jochugiku Co. Ltd, became a powerful player in the game of insect repellent products.
The variety we used to buy ~and still buy~ locally has always been a vivid, dark forest green. I don't know if this is indicative of a specific formulation, as I have also seen coils in tan and deep brown in other parts of the world. These mosquito coils have a very distinctive scent: sweetish like a sweet-shop burnt sugar note, intoxicating and resinous, with smoky, incense-y peppery notes; a mingled aroma that oscillates between sassafras, labdanum, cloves and camphor/eucalyptus. But how does the mosquito coil work, you ask. And what about the origin of that scent?
The active ingredients in mosquito coil are pyrethrins, naturally occurring in the seed cases of the perennial plant pyrethrum (Chrysanthemum cinerariaefolium, grown mainly in Kenya, the Med coast of Dalmatia in Croatia and in Japan), which has long been grown commercially for its insect repellent properties. Pyrethrins are chemically classified as terpenoids, being derived from dimethylallyl pyrophosphate, which combine by the action of the enzyme chrysanthemyl diphosphate synthase. The extract of the pyrethrum plant is solvent-extracted and yields pyrethrin I and II, cinerin I and II, and jasmolin I and II [the I tagged molecules are esters of chrysanthemic acid, while the II tagged molecules are esters of pyrethric acid]. That's enough of chemistry though. I'm pretty sure that besides the naturally gasoline and terpenes scent of the active ingredients in the coil there are additives which impart a more complex "bouquet" so to speak, rendering the coil pleasant smelling. The sticky brown residue that remains if you burn on a ceramic disk is viscous enough and bittersweet-smelling enough with amber-leather facets to suggest that a smidgen of labdanum incense is indeed used.
I have heard that the OFF mosquito coils sold in the US are also pleasant smelling with an incense whiff (and they're green too!), though I haven't been able to compare side by side so far. And mosquito coils are apparently not that new in that market either, which gives a nicely vintage-y factor to it all! Vintage coils even surface on Ebay, proving their cult status I suppose.
For all its sweet, smoky scent, certain precautions are of course de rigeur when using a mosquito coil, as with everything involving use of chemical and combustible materials: You should only use mosquito coils outdoors (being the equivalent of smoking 57 cigarettes if indoors!), never leave it burning close to anything in risk of catching fire (though it burns without a flame, it can transmit heat and produce sparks into combustible materials) and not use it more than occasionally -if that- if pregnant, especially during the 3rd semester. The pyrethroids in particular (used synergistically in some coils) are considered xenoestrogens [Garey et al., 1998], so take care if concerned, as should people with asthma and respiratory ailments. Also best avoid if you keep cats or fish, as it can be toxic to them if used by accident or they're exposed to the fumes. [For a full list of health/environmental concerns you can consult this article. ]
Pyrethrins are not fatal to insects in low doses ~especially to these modern, "mutant" ones which seems to have escaped from camp movie Mimic~ but they do have some sort of repelling action on them still. At the very least, these incense coils provide a smoky, scented ambience that is very evocative of the languor and mysticism of an exotic part of the world. Can't knock that.