Tag Archives: mosquitoes

Wine bottle drip irrigator

I don’t have a water source at my community garden plot so this summer I’ve been experimenting with drip-irrigation devices. My favorite so far is one that uses a wine bottle, and I’m sharing instructions here in case you’re bored out of your mind during the Covid-19 lockdown. You probably have wine bottles, but if you don’t I also give tips on how to use soda bottles and buckets.

Wine bottle drip irrigator

Instructions

  1. Cut the bottom off the bottle. The above shows a 750-mL bottle but a 1.5-L works, too. I own a Creator’s bottle cutter kit (it’s fantastic) but there are videos showing other techniques.
  2. Drill a hole through the cork to accommodate 1/4″ tubing.
  3. Cut a length of 1/4″ drip irrigation tubing so that it is 1/2″ longer than the cork. Put a small piece of tape over the opening of one end.
  4. Put a few drops of outdoor glue into the hole. Gorilla Glue is nice because it tends to expand, filling gaps in the cork.
  5. Insert the taped-up end of tubing into hole, pushing until untaped part is flush. Take off tape (that was there to make sure it didn’t get filled with glue).
  6. Once glue is dry, insert cork into bottle so that the 1/2″ overhang is sticking out.
  7. Attach an adjustable valve to the tubing.
  8. Attach a 12″ (or so) length of 1/4″ tubing to the valve.
  9. Attach bottle to a 36″ stake (1×1″ wood, 1/2″ bamboo, or plastic-coated metal) using wire. Make it extremely snug so that when filled with water it won’t drift down.
  10. Crumple up some tulle (or flexible screening) to form a filter plug near cork. Tamp down using a long rod. This prevents hole and valve from clogging.
  11. Attach tulle (or flexible screening) to top with two rubbers bands. One rubber band is fine but the second is backup in case sunlight degrades one. The screening keeps out debris, but also prevents mosquitoes from ovipositing when valve is closed (and bottle is filled).

Here are some closeups:

Once done, situate the irrigator in your garden so that you can easily see the drip and adjust the valve without fighting foliage or stooping. This is why the instructions above call for a short length of tubing rather than something that fully extends into the soil near the plant (where you couldn’t see it). Evaporation from a falling drop of water is probably non-zero but I think the ability to see the drip rate is worth it.

When you water drop by drop, slowly, the soil has time to fully absorb the moisture. Drip irrigated plants thus need far less water, sometimes dramatically less. Another benefit is that water isn’t constantly splashed onto leaves, something that can distribute as well as activate pathogens. Some plants simply don’t like wet leaves (don’t judge). And many plants (such as tomatoes) also benefit from being constantly hydrated, something that is hard to accomplish with normal irrigation. Finally, plants tend to take up fertilizer better when it is slowly delivered.

Plastic bottle drip irrigator

If cutting bottles is not in your skill set, soda bottles work fine. The only major construction difference here is that you need to insert a drip-emitter coupler into a pre-drilled hole in the cap. But that’s easy — the coupler just snaps in and seals even if you skip the glue step. I’d also recommend using a 2-L soda bottle, however, instead of the 750-mL one shown below. Plus make the stake 36″, not 24″ (too short, I’ve found), and use something sturdier than what I’ve shown. Bottle can be attached to the stake with wire or (as I’ve done here) with zip ties.

The screen on the top is absolutely critical. If the emitter clogs while you’re away on vacation and the bottle fills with water, mosquitoes will move in. Mosquitoes can complete development in as little as five days.

I also recommend cramming in some flexible screening into the neck of the bottle as shown above for the wine-bottle version. Round dish scrubbers will work, too.

Bucket drip irrigator

If you want to deliver gallons of water to a plant, buckets are the way to go. Below is one I made from a florist bucket I scored from Trader Joe’s. I used a coupler, inserted as per instructions for the soda-bottle irrigator. A bucket with a lid would be much better because it could keep mosquitoes out and would reduce evaporation. Even better would be a bucket with a clear lid so that you can quickly gauge water level. Or a clear bucket (they make them!). Elevate the bucket with bricks or mound of dirt so that the lowest part of the bucket is still above the emitter so that gravity can do its thing. You can also use much larger buckets (e.g., 40-gallon ones) and then attach multiple drip emitters via splitters or crosses.

In addition to the top screen (again, an absolute must for excluding mosquitoes), I recommend some sort of internal filter to prevent emitter clogging. I opted for a piece of weed-block cloth attached to some Gorilla tape.

The big disadvantage with ground-based buckets is that you can’t easily see the dripping in action. This means that you have to stoop down to inspect each irrigator to make sure the emitter hasn’t clogged, something that happens regularly if you haven’t screened and filtered properly. I prefer the elevated, bottle-based devices because you can walk through a garden and visually see that everything is dripping at a nice rate.

Alternative setups

Just a sampling of other people’s gravity drip systems.

Drip irrigation suppliers

Some hardware stores carry these supplies, but there are plenty of online distributors, too.

Experiment shows Spartan Mosquito Eradicator do not work

Experiments on Spartan Mosquito Eradicators fail to detect efficacy

According to research conducted in Florida, there’s no evidence that Spartan Mosquito Eradicators kill mosquitoes. Here’s the citation:

Aryaprema, V.S., E. Zeszutko, C. Cunningham, E.I.M. Khater, and R.-D. Xue. 2020. Efficacy of commercial toxic sugar bait station (ATSB) against Aedes albopictus. J. Florida Mosquito Control Association 67: 80-83. PDF

I summarize the two experiments and explore some of the implications, below.

Laboratory experiment

Below is a rough reconstruction of the laboratory experiment they conducted. In each of the cages (BugDorm-2120), 100 male and 100 female tiger mosquitoes (Aedes albopictus) were released, then monitored for mortality at 24, 48, and 72 hours.

Schematic of laboratory experiment based on description in Aryaprema et al. 2020.

Below are the cumulative mortality data for the three cages. Result: the Spartan Mosquito Eradicator filled with the provided packet ingredients (treatment) did not result in higher mortality. I.e., there was no evidence the device killed mosquitoes under laboratory conditions.

Field experiment

The researchers also conducted a field experiment using two sites that had large populations of tiger mosquitoes (because of the presence of tires). At each site they deployed five tubes (separated by 4 m), switching whether the tubes were “treatment” or “control” tubes every 2 weeks. A BG-Sentinel trap (without carbon dioxide) was used to quantify mosquito numbers every week.

Schematic of field experiment based on description in Aryaprema et al. 2020.

Below are the weekly numbers of mosquitoes caught in the BG Sentinel traps. Results: there was no evidence that presence of treatment tubes (filled as per company guidelines) reduced the numbers of mosquitoes at the sites.

Conclusions

Their overall conclusion: “Both laboratory and field components of our study show that the Spartan Mosquito Eradicator is not effective in reducing abundance of Ae. albopictus.” They speculate that the contents do not attract mosquitoes and that the holes on the device (~3 mm) are too small for mosquitoes to easily reach the fluid inside. They also highlight the need for an experiment to evaluate whether the active ingredient (1% sodium chloride) kills adult mosquitoes. I.e., even if mosquitoes were attracted to Spartan Mosquito Eradicators and could easily get inside, the salt might not be lethal. Per unpublished research, a 1% salt solution is, in fact, not lethal to adult mosquitoes.

Implications

The results of the experiments call into question the efficacy claims made by the owners of Spartan Mosquito. For example, the company says on the box that a 95% reduction in mosquitoes will occur within 15 days and will last for three months. The company also prints a graph on the label that indicates almost 99% of mosquitoes are killed by the end of this period.

Spartan Mosquito Eradicator efficacy graph

If the claims are false or misleading, which seems to be the case, states can classify the device as “misbranded” and issue stop-sell orders. Some have already done so.

These findings will also be important for the class-action suit that has been filed against the company and its owners. I.e., because there is now peer-reviewed evidence that the device does not kill mosquitoes, it will be considerably easier to prove to a jury that the company’s efficacy claims are false or misleading.

Finally, the results call into question the efficacy claims of the company’s newest product, the Spartan Mosquito Pro Tech, which replaces sodium chloride with boric acid. Although a boric acid solution can certainly be lethal if mosquitoes ingest it, the Pro Tech is based on the same design as the Eradicator and thus would not be expected to either attract mosquitoes or to allow them easy access to the fluid inside. The Pro Tech label, however, asserts that the device will attract and kill mosquitoes. It would be great to get a third-party assessment of whether those label claims are true.

Testing the Eradicator and Pro Tech at home

In regards to the question of attractiveness to mosquitoes, consumers can easily assess that at home with a zoom-equipped camera, binoculars, or a security camera. The idea is to be able to see mosquitoes near the cap (if they are there) but to be far enough away so as not to distract the mosquitoes. Ideally, capture a photograph or movie and get confirmation of what insects are actually gathering around the device (again, if any).

Per the above paper, you likely won’t see mosquitoes gathering around the devices. Per the company, mosquitoes will gather around the devices.

People can also assess whether mosquitoes are entering the devices by dumping the contents onto a white plate and taking a photograph. Ideally, share your photographs on Spartan Mosquito’s Facebook page — they’d love to see them. Or post on them on Twitter and cc me (@colinpurrington).

DIY mosquito trap using a plastic soda bottle

Here are instructions for building an indoor mosquito trap using a 2-liter plastic soda bottle. All you do is add some bait (honey, fruit, juice, sugar water, or some nectar-containing flowers) and place in a dark corner of the room. It works because mosquitoes seek out sugar, which they require to fuel themselves. Once inside the bottle they can’t get out.

The above instructions are a modification of a Taiwanese science-fair project that eventually went viral. The differences between the original instructions and mine are that (1) I don’t recommend adding dry active yeast, (2) I suggest sugar sources other than granulated sugar, and (3) I don’t wrap trap in black paper. The omission of yeast is because I don’t think the generation of carbon dioxide is necessary to attract mosquitoes to sugar. In fact, adding yeast likely reduces the attractiveness and causes the trap to fail faster.

The critical part of the original instructions is to deploy the device on the floor in a corner of a room. This is because mosquitoes love to hang out in corners — they are dark and relatively free of desiccating drafts.

Tips

  1. The original instructions suggest 50 g (~1/2 cup) sugar and 200 mL (~1 cup) water but the ratio probably doesn’t matter at all. Brown sugar is likely better than granulated (white) sugar because it has more impurities (some of which are volatile). A drop of rose water might make the sugar mixture more attractive.
  2. Make traps with different types of bait to see which ones are most attractive to the species that are local. Anopheles coluzzii, for example, seems to prefer papaya and banana juice over mango juice (Nignan et al. 2020). Other species might prefer oranges. Or, perhaps, durian.
  3. Replace your bait when it stops attracting mosquitoes. Perhaps every four days if you use fruit (Meza et al. 2020).
  4. If you use flowers, opt for ones that have nectar (if you know) and are light-colored. Or stick a small potted orchid inside the bottle — their blooms last for weeks.
  5. If you happen to have a plant with extrafloral nectaries, that’s a great bait that will likely last for a long time (when you’re on vacation, for example). Try a bunch of wild cherry leaves, for example.

Why it works

Mosquitoes are famous for sucking blood, but like many insects they spend most of their lives quietly ingesting sugar from flowers and rotting fruit. For example, here are some mosquitoes nectaring in the middle of the day:

So when mosquitoes find themselves trapped inside, they will zero in on whatever you have on the countertops — fruit, puddles of syrup, cut flowers, or even a dirty sponge. I don’t have photographs of mosquitoes eating fruit inside but Justin Yoshida (Thailand) does: on jackfruit, on apple slices, and on eggplant. Mosquitoes indoors are likely not especially picky about fruit type because the option is starving to death. Mosquitoes even fall into juice containers and die, apparently, as one restaurant discovered.

In case you’re skeptical that these traps can actually work, here’s a video by somebody who followed the original (science fair) directions and killed 9-10 mosquitoes in 24 hours:

Why it won’t work outside

Don’t bother using these traps outside (the recommendation of the viral versions). Mosquitoes prefer natural sources of sugar so they will likely ignore anything inside a bottle, regardless of how delectable you think the concoction is. The exception would be if you live in a desert and there are no plants near your house.

The traps will also not work in rooms full of flowering plants or decomposing fruit. Similarly, if your kids spill juice and soda everywhere, the traps won’t work.

Adding toxins to the mix

If you have a house free of small kids and meddlesome pets, you can add bit of boric acid to the solution to create an attractive toxic sugar bait (ATSB) station. Then, when mosquitoes ingest the fluid they will die even if they manage to escape the trap (it can happen). In fact, once you have a toxin in the fluid you can and should just get rid of the funnel part of the trap — its presence is likely a barrier to some mosquitoes even though it’s relatively wide (~2 cm). Instead, cut a 3 cm hole in the side and keep the cap on the bottle. Note that because these devices are indoors you don’t need to worry about the boric acid (or whatever) poisoning the pollinators in your yard.

The above is nicely explained by Andy Lee Graham:

One perk of adding boric acid is that fermentation will likely be slowed down, extending the life of your fruit juice. Note that fermentation will occur even though you haven’t added any yeast. Fungal spores are present everywhere.

© 2020 COLIN PURRINGTON