Mulch and Flies | How to stop flies coming to your garden

Mulch can attract small vinegar flies, march flies or black flies if you have mixed fresh manure through the mulch. Natural mulch like straw, bark mulch or sugar cane will not attract flies on its own so to avoid flies use mulch without fresh manure. Flies can sometimes sit on mulch if they are attracted to animal manures or urine that have previously been on the mulch, especially dog and cat urine.

Find out more about the relationship between flies and mulch in this article.

How to stop mulch attracting flies

The best way to mulch your garden without attracting flies is to use a natural mulch without adding any fresh manures. A layer of fresh bark, straw or sugar cane mulch laid on your garden beds will not attract flies as they are usually attracted to animal manures.

If you are using straw or hay from chicken yards, guinea pigs, rabbits, hamsters or mouse cages, add it to your compost pile first to break down. This will break down the manure and urine which can attract flies to your garden.

When can flies be attracted to mulch

I have experienced flies sitting on top of my mulch if dog manure or urine has been left on the mulch. The flies are actually attracted to the residue leftover from the waste rather than the mulch.

The easiest way to solve this is to remove the mulch and add it to your compost bin. Just remove any areas that the flies are attracted to and replace with fresh mulch,

Types of flies that can visit your garden

Flies are an insect from the order Diptera which means ‘two wings’. There are over 150,000 species of fly that can look like moths, the typical house fly or even horse flies which are around ½ an inch long¹. Although flies do like to breed in organic matter or vegetation, they do not tend to find a home in backyard mulch. Fly species that are common include the house fly, moth fly, vinegar flies or blowflies

Natural ways to control flies without chemicals

Using fly swatter is the most common way to control flies that end up in your house. While flies may exist outside, it is best to leave them as they are part of the natural environment and can be food for birds, spiders or lizards.

Sticky paper is a great, non-chemical way to control flies in your home. These sticky sheets can be hung up and attract and trap the flies without the use of chemical sprays.

Keeping flies out of your house is best achieved by using screens and well sealing doors. Fly screens placed over doors and windows is an easy way to keep them out. Moving quickly in and out of the doors ourselves gives the flies less time to make their way in. Check the fly screen regularly to make sure that there are not any holes for them to sneak through.

Removing mulch with flies

Mulch that is attracting a large amount of flies can be removed and placed in your compost bin to break down. The most likely cause of mulch attracting flies is that it contains animal manure that has not fully broken down. Add the mulch to your compost and mixing it through with other ingredients will help to break down the waste and stop attracting flies.

Use a compost bin with a lid to stop flies from coming in while the mulch is breaking down. Cover the mulch with a fresh layer of straw, fall leaves or sugar cane mulch to deter flies.

Used aged manures like composted cow manure or pelleted chicken manure will not attract flies as it has been broken down or processed.

Best mulch to keep bugs away

The best mulch to use to keep bugs away are fresh mulches that are not mixed with any fresh manure. Freshly made tree mulch which comes from chipped tree trimmings will smell fresh and will not attract flies. This mulch contains a mix of green and brown material and will break down naturally on your garden beds.

Fresh straw, sugar cane or lucerne mulch are great mulches that will keep bugs away. They are a natural mulch choice which is made of organic matter that will break down quickly to improve your soil. Lay the mulch on the surface 2-3 inches thick to allow the rain to drain through to the soil and avoid mold growth on your mulch.

Why flies are attracted to a garden

The top reasons flies can be attracted to a garden are because dog or cat waste is left on mulch or in gardens. Fresh chicken, rabbit, guinea pig or hamster bedding will also attract flies so if it is put into a gardens without being broken down first this could be a problem. Food scraps that are left open in worm farms or compost bins will also attract flies.

To avoid attracting flies to your garden, cover compost bins with a layer of fresh straws or hay and a tight fitting lid with small air holes that flies cannot enter. Cover worm farms with cardboard or a worm blanket and top with a lid to prevent flies from being attracted to the food scraps you are giving your worms.

Avoid placing food scraps like bread, cakes, cookies, meat and dairy in compost bins as this will quickly attract flies to the area. Even if the flies can’t make it into the bin because it has a lid, they can still be attracted to the area because they can smell the food.

Break down any animal bedding from birds, guinea pigs or rabbits first in a compost bin or pile to break down the waste before using it as mulch. Well composted animal waste can be used as mulch eventually but you will need to break it down to the point that it resembles soil. This will prevent flies from sitting on your mulch.

Mulch and Flies – Summary

Fresh mulch will generally not attract flies to your garden if it does not contain fresh animal manure and is a great addition to prevent weeds, improve soil and attract worms to your garden beds. Lay mulch 2-3 inches thick to allow rain to flow through to the soil and avoid it rotting and growing mold.

References:

1. Pest Control technical note, 2017, Victorian Government, Australia https://www2.health.vic.gov.au/-/media/health/files/collections/policies-and-guidelines/p/technical-note-number-23—flies.pdf?la=en&hash=649D2AEB44A7E686415BBA1134DB919D9F15D0E3.