In case you are looking for a way to kill mosquitoes without sprays, here are three types of traps that kill pregnant (gravid) mosquitoes that are searching for water in which to oviposit. Each is filled with water and decomposing plant matter (hay, compressed rabbit food, or leaves), then equipped with special lids (and sticky cards) that prevent females from escaping once they get inside. In addition to killing the females, any eggs that the female might lay are also prevented from developing by the presence of screens that trap the emerging mosquitoes from escaping. All of this happens passively, 24/7, all summer long, without the use of chemicals.
Every homeowner should have them. Coupled with other preventative measures (eliminating stagnant water, reducing excess vegetation, etc.), you can knock back mosquito levels and enjoy your yard again. Five units is probably sufficient for an average yard but I plan on making a few more this summer just to make sure.
Ideally, everyone on your block should have them, too, so if you are planning on ordering some you should first send a note to all your neighbors to see whether you can make a bulk order. E.g., if you order a lot of Biogents you can shave a few dollars off of each unit. Buying a bunch might seem like a lot of money but compare it to the cost (~$700) of having a company like Mosquito Squad spray your yard with pyrethroids every several weeks (every year). Using these passive traps also saves all the pollinators that are killed by those pesticides.
This post contains photographs and construction tips for a killer craft I made: an autocidal gravid ovitrap. Pregnant females enter the trap, lay some eggs on or near the stagnant water within, then are prevented from exiting and die. Their progeny also die because a screen at water level prevents larvae from reaching the surface to obtain oxygen. When similar traps have been deployed they bring down mosquito levels substantially and thus are quickly becoming one of the main ways to prevent mosquito outbreaks and disease. Every homeowner should have six. They’d make wonderful gifts.
The design features a clear dome that helps trap the females when they are done ovipositing (they go for the light), plus a completely unneeded observation window so I can watch the larvae and pupae (fun for the whole family, plus good for demonstration purposes). It borrows general methodology from gravid Aedes traps (GATs) designed by Dr Scott Richie (James Cook University) and colleagues that recently made news on NPR (here’s an overview; here’s their paywalled journal article). I’ve designed mine to capture species that also lay egg rafts, so it’s not just a GAT. My design doesn’t use insecticide because I wanted the odor of developing larvae to be an attractant to other females (it is, by the way).
What you need
6″ plastic pot
clear dome from cake store
metal coat hanger
small neodymium magnet
silicone adhesive glue
1-L soda bottle
1/4″ foam weatherstripping
black spray paint
Dremel tool with cutting bit
drill with drill bit
safety glasses (when Dremeling)
If you’d like to see photographs larger just click on first image and navigate like a slide show. There are many ways to construct these so if you build one and it looks completely different, don’t worry. This is because if your device is the only stagnant water around, females will use it.
Buy an 8″ cake for the clear dome on top. Eat cake.
Cut off bottom of pot, use knife to smooth edge.
Draw circle on dome where funnel will drop in.
Cut hole in dome with Dremel to accommodate funnel.
Glue funnel onto dome. Use Goo Gone to remove labels.
Fit funnel with optional hardware cloth grid.
Cut hole in pail lid with Dremel, then smooth the cut with a knife.
Cut observation window into side of pail.
Cut rectangle out of soda bottle for viewing window.
Glue soda bottle plastic onto inside of observation hole.
Apply bead of silicone sealant to outside of observation window.
Cover observation window prior to painting.
Paint outside of pail and lid black.
Attach clear dome to pail lid with anything but Goop
Bend coat hanger into diameter equal to inside diameter of pail.
Staple fabric screening onto coathanger.
Affix weatherstripping to inside of pail to support the screen.
Make handles for the screen out of paperclips.
Drill drain holes so that water line is barely above screen.
Fill pail with rainwater not tap water.
Add old leaves from gutter, cat food, etc. to bait the water.
Add wood (and/or cloth strips) for egg laying.
Hang sticky card by paperclip held by neodymium magnet.
Situate trap in thick vegetation, protect from rain somehow.
I’ve only just deployed it and it’s rather cold right now so I don’t have any victims yet. But I’m optimistic and am posting now with the hope that somebody will have suggestions on how to improve the design (I’m making more). One improvement I’m definitely going to make is to drop the funnel lower into the dome so it’s harder for females to accidentally fly straight up to escape. And pro-tip if you make the above: attach the lid to pail when spray painting to avoid unwanted buildup where they attach.
I’m also posting in the off chance that a biology teacher might take an interest. Having teams make these would be really fun and then they could deploy them in the woods near the school: bonus points for team that traps the most mosquitoes. It’s fun like the classic egg-drop lab in physics except useful. Students would then take their projects home where they’d continue to be useful. Would make for a great Girl Scout Gold Award / Eagle Scout project.