Having inspected over 70 yards this year so far, it is likely there are mosquito breeding sites in your yard, nearly everyone has at least a few! The top 10 mosquito breeding sites that we list here are probably a huge part of the problem you're experiencing with mosquitos. Eliminating or larviciding those breeding sites is key to reducing mosquitos and maximizing the results you’ll achieve using our standard baiting station treatments. But first, you have to find them. If you aren’t paying us to do it for you (the optional add-on), you can use this post as a guide for how to inspect your yard and eliminate mosquito breeding sites.
First, what makes an ideal breeding site for mosquitos? Mosquitos generally need standing water to last at least a week. They also need the water to be stagnant or slow moving, and it cannot contain an abundance of fish, which will eat the mosquito larva. With this criteria in mind, places in your yard where water pools for a day or two after a rain, the creek in the park behind your house, and your koi pond are unlikely to be the culprit. Typically, especially in urban and suburban areas, mosquitos are breeding in artificial containers commonly found in your yard, as well as your neighbors’ yards.
Taking the data from just over 70 houses we inspected this Spring, here are the Top 10 mosquito breeding sites you’ll find in your yard. Definitely check these out, but remember to do a thorough walk through of your property looking for anything unique to your property that could be holding stagnant water. You can use BTI based products like mosquito dunks and mosquito bits to larvicide any problem areas you cannot eliminate. Regardless of what you are larviciding, be sure to apply the larvicide at least once a month.
1. Downspout Extenders and Drainage Systems
By far the worst offenders! Almost every house has this issue. Every fold in the corrugated piping is a separate breeding site that mosquitos, particularly tiger mosquitos, can use. Because it is covered from the top, it takes much longer for the water to evaporate. That is the case whether you have the simple $5 plastic extender shown above or an expensive drain pipe built into the ground. Additional issues can come from other parts of your drainage system. French drains, pop-up drains, drains at the bottom of stairwells, and improperly sloped drain pipes (whether underground or above ground) are common problems too.
The best solution to this issue is to eliminate it. You can do that by using straight pieces of aluminum downspout material or PVC in place of the corrugated plastic. You can buy an adapter to convert from aluminum downspout to PVC. An even simpler solution is to use a splash block instead. Check to be sure water drains all the way through the pipe. If it slopes down, then up, then back down, water will pool inside. Correct the slope so that it gradually slopes downward away from the house. Another option is to exclude mosquitos from entering the drainage system to begin with. You can put pantyhose over the end of the outlet and secure with a rubber band. It is important to remember that mosquitos can access from the inlet as well. Seal any gaps between the downspout and the extender and consider a leaf guard at the entrance to the downspout.
If you already have french drains, pop-up drains, underground corrugated pipes, or a drain at the bottom of your stairwell, it's not reasonable to eliminate it unless you're already planning a redo. In this case, you will want to larvicide. You can also do this for the corrugated downspout extenders above ground until you're able to replace them with something else. Using mosquito bits, crushed up mosquito dunks, or preferably a combo of both, you want to get these products into both the top/inlet and bottom/outlet of the pipe, as best you can. From the bottom/outlet, throw the bits in as far as possible, shaking the pipe if possible to get them further back into the pipe. From the top, simply drop them in and apply liberally since rain will carry some of your larvicide down the pipe. You can usually find a gap between the downspout and the extender.
Another option would be to deny access. For the corrugated downspout extenders, cover the end of the extender with pantyhose and use weatherproof duct tape to seal the gap between the downspout and the inlet of the extender. The gap can also be sealed when the downspout runs into an underground pipe. The goal is to make it impossible for the mosquitos to get to the standing water, especially when it is not possible to eliminate the water, and Larviciding products might be washed out by rain.
You want to apply the larvicides to any pop-up drains (lift up on the middle part), drains at the bottom of the stairwell (push them through the grate), and french drains (any access point you have) as well. Generally gutters are not going to hold standing water for 7 days, but it is still a good idea to get your gutters cleaned regularly and to make sure they are sloped correctly.
2. Stacked Plastic Pots and Saucers
It's easy to rack up quite the collection of plastic pots, but storing them incorrectly can also net you quite the collection of mosquitos! Yes, they do have drain holes in the bottom (or they should). However, large stacks of them like pictured here almost always have at least one pot that doesn't drain correctly. Rocks, soil, mulch, plant labels, and other debris can build up and block the drainage holes.
There are myriad ways to solve this issue. You can simply flip them over so the stack is upside down. Another option is to store them covered in a shed or garage. You can also just get rid of them entirely, preferably by donating them back to a nursery. Just don't leave them out like this!
Changing gears to planters, the issue here is the saucers. The saucer below the pot can hold plenty of water for mosquitos to breed. The best solution is to just get rid of the saucer, or attach small feet to it and drill holes in the bottom. You can buy plant pot holders online that won't hold standing water. If you really feel like you need the saucer to hold water, you can either larvicide with bits or dunks, dump the saucer and put it away when done watering, or use unfinished, unpainted terra cotta. Terra cotta will naturally soak up the water over time and shouldn't hold standing water for 7 days.
Always make sure that plant pots kept outdoors have drainage holes. If it's being used for something like a water garden or bog garden, apply mosquito dunks to larvicide.
3. Garbage Cans Without a Lid
This one is very straightforward. It is quite shocking how many houses have garbage cans with no lid, an unused lid, or a broken lid. Without a proper lid, water will collect in the trash can. Either get a tight fitting lid for the trash can or drill holes in all 4 corners of the bottom of the can to allow drainage. You could also opt to store the trash cans covered.
4. Kids’ Toys
You can tell pretty quickly if there are younger kids making use of the yard, because there are often toys scattered everywhere. Most of these toys are plastic and don't have drain holes, so they will hold standing water in the right orientation. I'm sure you don't need another reason to tell your kids to pick up their toys, but if you do, mosquitos breeding in them is a good one!
Management of this issue can be done by storing the toys covered or walking around the yard weekly and dumping out all of the toys. One of the biggest culprits I've seen are plastic pools. No matter which orientation you put them in, water will pool in them. They really need to be stored covered. Decks often do not provide sufficient cover. But, don't use a tarp either!
5. Tarps and Covers
Tarps and other tarp-like covers are probably the sneakiest place that mosquitos regularly use to breed. There may be hundreds of folds in the tarp, but somewhere in there, it's likely that one of them holds standing water. The folds prevent the water underneath from evaporating, so small pockets of water can last a long time. Grill covers are another common issue. If the tarp or cover is not in use, it must be stored covered.
If the tarp or cover is in use, it must be the appropriately sized, pulled taut, and secured without using the weight of an object to hold it down. Preferably, don't allow the tarp to touch the ground. Water often pools right at the crease where the tarp bends when it hits the ground. Pulling the tarp taut will help eliminate folds, which you should minimize.
Preferably, use a cover designed for what you are using it for. Instead of using a tarp to cover firewood, get a cover designed for protecting firewood. Securing the tarp with string or bungee cords is preferable. When you use the weight of an object to hold down the tarp it creates folds and pockets right by the heavy object.
If your yard is filled with tarps and you have no idea what to do, you can throw or sprinkle mosquito bits all over the tarp for a temporary fix.
6. Bags of Soil, Mulch, etc.
This one is very similar to a tarp. Folds in a sheet of plastic are bad. Generally, you see this with bags that have been opened. If a bag of soil or mulch has been opened, just go ahead and store it covered. If there is only a little left in the bag, you could also transfer the remaining contents to a plastic pot with drain holes and throw the plastic bag away.
7. Gardening Tools
Where you store your garden tools, preferably covered, can make a big difference. It can be easy to leave out a watering can or a bucket full of dirt, but that can come at a cost after it rains and fills up with water. I often find mosquito larva in buckets intentionally filled with water for the purpose of sharing plants that were recently dug up. While it's great to share plants, be sure to throw a piece of a dunk in there, just in case you don't give the plants away as soon as you expected. Wheel barrels should always be stored upside down or vertically. If not stored covered, watering cans and buckets should be stored upside down.
8. Random Trash and Forgotten Items
A deflated kickball under the trampoline, an old yogurt container mysteriously under the deck, an empty potato chip bag that probably blew in on trash day. I've found mosquito breeding habitat in all of these! Just like volunteers participating in sweep the creek or plogging, you too should make an effort to pick up litter, whether put there by you or blown in by the wind. Be sure to check under dense bushes as that is a spot that often collects trash blown into your yard.
9. Tree Holes
Tree holes can come in many shapes and sizes, occur at any height, and be caused by disease, growth form of the tree species, or cavity nesting birds. While you may not be able to locate a tree hole dozens of feet above you, you should inspect all of your trees for tree holes at accessible heights.
Large mature trees will generally have them where a large branch previously split off, or at the intersection of major branches. You should also check the root flare for any cavities occurring at ground level. Crepe myrtle trees, especially older ones, seem to be the most likely to have tree holes. Do not attempt to drill a drain hole into the tree. This one should be handled by larviciding with bits or dunks.
10. Tires
It was a shipment of used tires that brought tiger mosquitos (Aedes Albopictus) to North America originally. Tire shipments within the US are believed to have aided in their rapid spread. It goes without saying, then, that tiger mosquitos love breeding in tires. Whether a tire swing or just a random old tire residing in your yard, tires can be a great breeding site for mosquitos.
If your tire is now a swing, you can probably drill a hole in the bottom for drainage. A small chunk of a dunk will handle it as well. If it's an old tire you no longer need, just get rid of it. If it's an older tire you do need, it needs to be stored covered, because tires hold water in any orientation.
Honorable Mentions:
- Bamboo - Dead, cracked, or cut culms can hold water in the space between the nodes. Tiger mosquitos share the same native range as several species of bamboo and can use it as a breeding site. Removing the bamboo is the best solution.
- Fence Posts - Make sure there aren't any caps missing, and make sure any remnants of an old fence post (such as the concrete that held in place) are filled in or removed.
- Rain Barrels - Just throw a mosquito dunk in, unless you are absolutely sure that mosquitos have no way to access the water.
- Bird Baths - Just throw a mosquito dunk in, unless you have a strong fountain or you are certain you will remember to empty it at least once a week.
- Yard Decorations - Candles, garden gnomes, umbrella holders, flag holders, decorative bottles or vases, etc. can all hold water. If you can add drainage holes that solves it, otherwise, either remove/replace or larvicide with small pieces of a mosquito dunk or mosquito bits.
- Storage Containers - Be sure to buy storage containers intended for outdoor use. The lid and any other portion of the container should not be able to hold water. Make sure the lid fits tightly and does not have any cracks or holes. If you find water is getting inside, you can also drill holes in the bottom for drainage.