Does Mulch Attract Flies? Avoid a Garden Infestation

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Mulching your garden is a wonderful way to retain moisture, suppress competition, and feed the soil. Since organic mulch breaks down over time, you may be wondering if the decomposition attracts garden pests. Does mulch attract flies? Find out here!

The look of a freshly mulched garden bed is so appealing and I’m here to tell you that you don’t have to skip using mulch for fear of a fly infestation.

Types of Mulch

There are so many options when it comes to mulching your garden and outdoor spaces. The type of mulch you choose will influence its attractiveness to insects both beneficial and unwanted.

Adding organic material to your garden will improve soil structure and productivity while reducing weeds and improving moisture retention. Mulch allows your crop plant roots to have access to all the resources they need with reduced competition from weeds.

Different types of mulch have different benefits and risks when it comes to avoiding unwanted pests.

Wood Chips

Wood chips are a common mulch choice for home gardeners. They are great at suppressing weeds and holding in soil moisture. Wood mulch also provides an aesthetic appeal to a home landscape. The look of mulch can be very appealing.

Wood chips break down slower than leaves, straw, or grass clippings, so they don’t need to be applied as often.

Wood chip mulch can attract beneficial fungi that improve your soil conditions and your plant growth. There is some evidence that wood chip mulch can pull some nitrogen from the top layer of your soil, but if you don’t till the wood chips into your soil, these effects are minimal and short-lived.

You can prevent unwanted insects in your wood chip mulch by keeping moisture levels in a reasonable range and not applying a layer that is too thick. Too much moisture can attract flies.

If you are mulching around your house, cedar mulch is a great option. Cedar trees have naturally occurring chemicals in their wood that repels insects.

Grass Clippings

Grass clippings are a mulch that most home gardeners have access to. While they break down quicker than wood chips, they do a great job of holding in moisture and preventing weeds. If you water your garden beds too much, grass clipping mulch can get slimy and attract flies, but if you let the grass clipping mulch dry out between watering intervals, this won’t be a problem.

Leaves

Leaves are a wonderful addition to your garden as mulch. A 2-3 inch layer of leaves is excellent at weed control and holding in soil moisture. Leaves can get slimy if you water too much, which can attract unwanted flies. Just make sure you check the soil with you finger to see if it is dry before you water. If the soil under the leaves still feels wet, you don’t need to water.

Straw

Straw can be a wonderful mulch material if you make sure that it isn’t contaminated with pesticides that may harm your garden plants. Some pesticides don’t break down very quickly and if the straw is contaminated with these types of chemicals, you may have damage to the plants in your garden.

Tomatoes are especially vulnerable to pesticide damage, so you want to make sure you understand what chemicals were used on the fields where the straw came from.

Pine Needles

Pine needles are another great option for mulching your garden. Their structure prevents matting, and they don’t get slimy when they are wet. Pine needles do not attract flies.

Large amounts of pine needles can acidify your soil, so for best results, test your soil periodically to monitor soil pH and nutrient levels.

Compost

Well-rotted compost can be used as a mulch if you have a large quantity available. I like to use bulk compost from my local garden store. I can buy a truckload and apply a thick layer around my plants.

You want to make sure any compost you use is completely finished. If your compost piles still have visible food waste or smell bad, cluster flies, blow flies, and fruit flies will be attracted to it. If your compost smells like sweet dirt, it is ready to go on your garden.

Does Mulch Attract Flies?

Flies are sometimes attracted to mulch because of the fungi and bacteria that are breaking down the organic matter. Bacteria and fungi are attracted to moist environments. Flies are always looking for a food source, and sometimes the fungi and bacteria that can grow in mulch is appealing.

Some fungi produce fruiting bodies called stinkhorns. Stinkhorns produce a foul odor that attracts house flies and fruit flies. If your mulch starts to smell bad, it is important to get rid of the fungi by spreading out the mulch in a thinner layer and letting it dry out. Keeping your mulch on the dry side helps prevent unwanted pests.

I have used grass clippings, leaves, and compost in my garden for over a decade and I’ve never had a problem with flies. Using just a few simple preventative measures like carefully monitoring moisture content in the mulch and not applying thick mulch can prevent any problems with flies.

Pest Control

Making your landscape attractive to birds, frogs, and predatory insects can help reduce and control fly populations. Attracting ladybugs, praying mantis, frogs, and birds to your garden area is a great way to control unwanted insect pests.

You can also control unwanted flies in your mulch by changing the type of mulch you use from year to year. I like to rotate using grass clippings, leaves, and compost.

If the fly population is higher than you would like it to be in your mulched garden, you can use yellow sticky traps to capture flies. While this can be very effective, you may also capture bees and other pollinators, so you will want to monitor your traps to make sure you aren’t killing too many beneficial insects.

How to Apply Mulch to Prevent a Fly Infestation

One easy way to prevent a fly infestation is to spread your mulch around your plants immediately rather than creating a mulch pile. If mulch is always in a thin layer rather than a large pile, harmful bacteria and fungi won’t grow. Mulch piles are often the source of fly problems.

Apply mulch after your plants are established and growing. I like to apply mulch around my plants 2-3 weeks after they have germinated or been transplanted into the garden.

I roll out a layer of unbleached paper around my plants and mulch beds with 2-3 inches of my chosen mulch.

If you allow the soil around your plants to dry out before you apply the mulch, you will reduce your risk of detrimental fungi and bacteria growing in the mulch.

Delayed mulching also allows the soil to warm up in the spring which helps plants grow. If you mulch beds too early in the spring, the soil temperature will stay cold and could hinder plant growth.

These simple steps will help you prevent flies from proliferating in your garden.

The Benefits of Organic Mulch Outweigh the Risks

The good news is the risk of a fly infestation does not deter me from using organic mulch in my garden. I have been using organic mulch for over 10 years and I have never had an infestation of flies.

While inorganic mulches such as rubber mulch can prevent any problems with flies, I don’t recommend introducing inorganic materials into your vegetable garden. Unwanted chemicals can leach from rubber and plastic into you soil and can be very hard to remove.

If you don’t overwater, you don’t pile the mulch too thick, and you don’t use fresh food scraps or waste, you will have minimal fly problems. The benefits of mulch far outweigh any risk of attracting flies.

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