Whack the mozzies

Having nearly conquered my entomophobia (in my younger years, most any bug would creep me out), at age 58 I have not yet found a place in my heart for mosquitoes.

I date my intolerance to the first moon landing. I was four. My folks were in the living room with the grainy black-and-white images of Armstrong and Aldrin on the TV, airing too late, by parental decree, for me to watch. Yet down the hall in my bedroom I was wide awake, missing the big moment ...and battling skeeters. I eventually decided to join my parents, who by then were too entranced by what they were seeing to send me back to bed. Years later I'd smile upon learning that Aldrin's nickname was Buzz. 

At Poggiosole, the presence of mosquitoes, particularly around Begonia's and Le Rose's outdoor patios from mid-afternoon onwards, is the number one complaint from guests. Example (in Polish) from an otherwise glowing review on Booking:

"Komary, mimo sporej ilości „odstraszaczy” w które wyposażył Nas właściciel"

Read that aloud and you can practically hear them buzzing! Yes our bedroom windows have screens, yes we hand out citronella candles and spiral-shaped mosquito coils (known locally as zampironi) but the nippers have tended to prevail.

So this summer I decided to throw down a few thousand euro on a BioZanz nebulizing system designed to whack the mozzies.

Picture an above-ground irrigation system, with programmable Rainbird-style timer, but operating at 20 bar with 60 nebulizing nozzles spaced 2 to 3 meters apart (many are set in our hedges). This setup disperses an aqueous suspension of neem and citronella oil (the latter smells nicer, the former is funkier but a reportedly more potent repellent) at regular intervals on the grassy areas surrounding the patios and swimming pool. According to the BioZanz sales rep, an effect equivalent to "hundreds of citronella candles" can be attained (now that does sound like a stretch, and the candles would surely be prettier, but I digress). As a coup-de-grace a 1% pyrethrin solution is released pre-dawn, when most mosquitoes are resting on leaves and other damp surfaces, ready to fly their first "sorties".

Both the repellents and pyrethrin (derived from the powder used to make mosquito coils) are made from plants, and none persists for more than a couple of hours in sunlight. Of course, although marketed as "bio", once the nebulizing system is installed it can dispense most anything, including more potent and persistent synthetic insecticides and repellents. But, at least to start, we'll load natural, more volatile substances and cross our fingers.

Our BioZanz will be operational from the second half of July. Watch the space below for updates on its efficacy ⚡️☺️

Update, April 25, 2023: Last summer's results were mixed. On the plus side, guests appreciated the misty clouds of neem and citronella oil issuing from the hedges surrounding the pool and most liked the "exotic smell" of the oil blend. On the minus side, mosquitoes, while reduced, were still a problem. This was especially concerning given that last summer was exceptionally dry. Had the system really done its bit, adding its effect to last year's drought should have resulted in no mosquitoes at all. The supposed "coup-de-grace" of 1% natural pyrethrin touted by BioZanz's sales rep ended up being nothing of the sort. What to do when a sales pitch is exposed as hyperbole? Before tossing the system and writing off the purchase, talk to the techs. When one of BioZanz's most senior technicians returned this month to test and fine-tune our setup, he repeated the advice he had given me when he installed the system last year: to really whack the mozzies, persistent pesticides are needed. That's because persistent compounds, besides being synthetic, stick around to kill insects for days, even weeks after being dispersed (I've been reading up on the half-lives of various synthetic pyrethrins). So drom today our pre-dawn daily emission of insecticide will, on alternate weeks, consist of a 1% dilution of Arpon Diazipol, a pyrethroid blend of cypermethrin (volatile) and deltamethrin (persistent). We'll continue to use natural pyrethrin for our pre-dawn misting the rest of the time. Impact on bees should be minimal given that bees are in their hives at 6 AM. The dilution I'm programming is said to not be dangerous to dogs (or people). Cats are another matter, since they lack an enzyme that allows dogs to metabolize both cyper- and deltametrin, but we've never had guests bring cats, and our own house cats will be brought indoors on the evenings prior to each Arpon misting.

Update, June 24, 2023: Call me distracted, but it took me almost two months to piece together why, since our April re-opening, our BioZanz machine was springing leaks every couple of weeks and pouring significant quantities of highly concentrated Arpon liquid onto the floor of our laundry and storage room. After two such failures, two visits by BioZanz service technicians, and a conversation with one of the machine's inventors, the culprit was identified. Arpon Diazipol is a petroleum-based (versus water-based) compound, and its volatile components are chemically incompatible with the BioZanz machine's O-ring seals, as well as with the teflon-reinforced rubber tube of the machine's peristaltic pump. Once I began to suspect Arpon as the cause of these mishaps I got a scolding from BioZanz, who also informed me that by using an unapproved product I had voided the unit's warranty. But then, graciously, on the condition that I thoroughly clean the mess I'd made before their tech arrived, they replaced the ruined peristaltic pump and nozzle circuit exit valve at cost.

Final update, January 6, 2025: With over two years to get to know the system and, more importantly, the array of substances that can be used as either insecticides or repellants, we have settled on a "middle ground" between natural and synthetic (read persistent) repellants and toxins. Our afternoon and evening one-minute mistings of essential oils are programmed at intervals of 40 minutes until around 10:30 PM.

The "bugs" paragraphs of our Safety handout

For these we've settled on a 2% acqueous solution of neem, eucalyptus, and citronella oils: definitely pleasant-smelling and with a moderate repellant effect. And having learned that only a synthetic and persistent pyrethrin will have significant impact on our mosquito problem, I researched and found an alternative to Arpon: a product called TATOR. Straight from the bottle, TATOR has high concentrations of cypermethrin (volatile) and tetramethrin (moderately persistent, with a half-life of around 14 days). Amongst TATOR's biohazard labels is one that unamiguously categorizes it as toxic to humans, especially during pregnancy. However, diluted through our nebulizer's peristaltic pump, the concentrations we end up misting over and around our grounds are 0.2% cypermethrin and 0.04% tetramethrin. These are emitted daily between 6:25 and 6:30 AM and, from mid-June through mid-September (peak mozzie season), again between midnight and five past midnight. Bees are in their hives and guests are (usually) in bed or at least indoors. Our cats, like all cats, are nocturnal, and so probably at some risk, although our vet has assured us it's minimal. Result? In 2024 these once or twice-daily emissions or TATOR nearly eliminated mosquitoes on the property, while bees continued to buzz about our lavender and rosemary bushes. Of course, when guests arrive, we inform them of the BioZanz system and the compounds it emits. Any guest can request that the system's programming be either changed or suspended during their stay. And from mid-October through March the nebulizer is winterized and disabled, giving our local ecosystem a chance to recover. Working this way, Poggiosole's mozzies do appear to have been whacked.