Attach a 12″ (or so) length of 1/4″ tubing to the valve.
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.
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.
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.
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.
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.
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.
Replace your bait when it stops attracting mosquitoes. Perhaps every four days if you use fruit (Meza et al. 2020).
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.
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.
In nature, tunnel-nesting bees are perfectly happy to use logs riddled by boring beetles or piles of dead plants that have hollow stems. That habitat is often in short supply in many yards, however, so it’s necessary to provide hotels if you want to attract them. These hotels can be as simple as a large coffee can filled with hollow reeds … or as elaborate as the three-level one I built. The bees really don’t care.
Types of nesting material
DIY bee hotels can be filled with routered nesting trays (you can buy these or make your own, if you’re handy), wood blocks with paper inserts (these inserts can be purchased), wood blocks or logs with drilled holes (unlined), or just sections of hollow stems (by far the easiest). Or, like house in the photo below, a mix. A hotel should have a roof to keep the tunnel entrances relatively dry, should be situated to get morning sun, and be approximately 5 feet off the ground (so you can enjoy watching them).
Below is a photograph of my other hotel. It’s smaller and is set up in my front yard to entertain people who walk by. Tunnels are all unlined drilled holes, plus milkweed stems. Holes in the blocks are varied because I want to attract a variety of solitary bees (It’s an attempt to get neighbors interested in native bees.)
Swap nesting materials regularly
The ideal bee hotel is one that allows all the nesting material to be removed each year (or so). By installing fresh nesting material, new tenants each spring will get to move into tunnels free of kleptoparasitic pollen mites and pathogenic fungi. Another benefit of removable nests is that you can remove sections as they get filled, allowing you to replace the spot with the same type of tunnels or with tunnels that have different diameter to cater to a different bee species (there are hundreds). Below are examples of my hotel with different configurations (my 2020 version, on right, is a bit boring).
What do you do with the nesting material after you remove it from the hotel? I put mine into a large cardboard box that has holes in the sides and at the top, then store in my unheated garage for the winter. In mid March (before bees in my area start to wake up) I put the box outside in a spot that is dry and gets good morning sun. Then when bees emerge from their cocoons they can escape from the box but are disinclined to re-inhabit the nesting tunnels they emerged from. Here’s a view of the nesting material inside my emergence box.
After several months outside (e.g., in August, long after the last resident has emerged) I take everything back into my shop and redrill holes and sterilize the wood. Then I can reuse blocks in future years.
Lately, I’ve been thinking that I should move entirely to a system where I can sort through pupae at the end of the season. E.g., as summarized here. The reason for this is that I’d like to remove (kill) the kleptoparasitic mites (pic) and Houdini flies (pic) that are likely destroying many of my solitary bees. To enable this process I am going to start using paper straws to line all the tunnels. These straws can then be removed and unwrapped and the contents examined. Below is a photograph showing how drilled holes can be lined with paper straws — just fold over the back overhang and seal with foil tape.
Several companies sell sturdy (and easy to unwrap) paper straws as well as cardboard tubes that can easily accommodate the straws (i.e., you don’t need to drill holes in wood).
Another way to sort through pupae is to use routered wood trays, which you can buy or make (with a router or a table saw). Although some types of trays are better used with straws (to prevent mites from moving from tunnel to tunnel), others fit snuggly enough to be used without them. On my list of things to do is to make some routered nests that are sealed on one side with Plexiglas so that I can observe the bees within (such hotels can be purchased, and are beautiful).
To keep everything dry on something this tall you need a generous roof overhang. Mine extends 5 inches beyond the front of the shelf, plus the wood sections and reeds are set back from that by another inch or so. If you have a shorter house you can have a smaller roof.
For larger hole sizes you want, ideally, 6 inches of depth. Shorter (4″) tunnels are fine but can result in a male-biased brood sex ratios. If you want to encourage population growth, encouraging the production of females is important. So buy long bits (I really like my 5/16″ auger bit, shown in drill below).
Burning the front of the wood allows bees to more easily find their holes, plus the darker surface causes the wood to heat up faster in the morning sun.
Avoid treated lumber or fresh cedar. Per rumors on the internet, those types of wood can result in the death of the larvae. Pine is fine but I think harder wood is preferable because the drilled holes tend to be smoother.
For cutting reeds to size, I highly recommend using a cutoff disc on a Dremel tool instead of pruners. You can get a really smooth surface with a Dremel.