Does Mulch Attract Bugs?

Does mulch attract bugs? The truth is, mulch provides shelter and protection for many different species of insects. That’s not necessarily a bad thing. Bugs and insects help organic mulches decompose. The problem is that some bugs and insects, such as termites, carpenter ants, sowbugs, millipedes, earwigs, and centipedes can be potentially harmful, attacking plants and buildings.

One way to prevent damage from, and control the effects of, unwelcome troublesome insects is to choose a mulch that keeps bug problems to a minimum. Adjusting your mulching techniques can also help encourage healthy plant growth while reducing pest problems. 

What Is Mulch?

Mulch helps control weeds, improve moisture, regulate soil temperature, and prevent soil erosion. It improves the soil. Organic mulches are made from materials such as leaves, grass clippings, other plant and vegetable matter, straw, wood chips, and bark. Other non-living materials include pebbles, lava rocks, seashells, plastic, and rubber.   

Wood mulches are among the most popular used by gardeners due to their attractive appearance, ready availability, and relatively low cost. Wood chips from cedar trees and hemlock contain an oil with an odor that repels bugs such as moths, ticks, snails, slugs, and pillbugs. Grade A pine doesn’t attract insects looking for nesting material because it doesn’t contain any living organic matter.

Non-wood organic mulches include shredded leaves, grass clippings, and other plant and vegetable matter. Organic mulches provide minerals and nutrients to the soil that helps nurture the roots of plants. Straw mulch indirectly affects populations of harmful insects by favoring species of larval predators that attack pests. A study in Guelph, Ontario, found that organic mulches, including coffee bean chaff, cocoa shells, and peat moss, designed to repel bugs, seem to also work against termites. 

Inorganic mulches are made up of non-living materials such as pebbles, lava rocks, seashells, plastic, and rubber. The Guelph study found that decorative stone and rubber mulch were completely effective against termites. Rubber mulch is made of recycled rubber tires. It comes in a variety of colors and helps keep bugs at bay. Aluminum foil or silver plastic mulch used around vegetable plants may significantly reduce certain insects and the viruses they may carry.

Plastic mulches create a reflection that confuses insects and keeps them away from your garden. They are only effective when the leaves of your plants do not block 60 percent or more of the soil’s surface. Straw mulches are effective for reducing the population of insects and keeping bugs away from your cucumber and squash plants. They also deter bugs from laying eggs and multiplying in and around your garden. It also protects plants from the spread of fungus and other diseases that cause plant rot. 

Organic vs Non-Organic Mulch

There are two main forms of mulch – organic and non-organic. Organic forms of mulch are particularly beneficial for increasing the moisture content of the soil by reducing or slowing evaporation. It also helps feed the fertility of the soil as it decomposes. Organic mulches can provide benefits that inorganic ones simply can’t. Unfortunately, some of its beneficial characteristics also make it attractive to some insects such as termites, sowbugs, pillbugs, millipedes, earwigs, and centipedes. Some of the mulches can also provide shelter for some cockroaches, rodents, and provide food for termites. 

One difference between organic and non-organic mulches is longevity. Because organic mulches decompose to benefit the soil, they will not last as long and need to be replaced more often. Non-organic mulches do not provide the soil-nutrient benefits of organic mulches, so they will last much longer because they don’t break down. They’re also less likely to attract above-ground pests, though their insulation of the soil can still create harborage areas for below-ground pests, such as termites. 

Does Mulch Attract Termites

Termites love the moisture created by mulch and use it as cover for exploring the area by digging thin tunnels and looking for food – wood. While they may not feed on the mulch, the presence of the mulch increases a termite’s ability to survive around your home if they’re already present.

Termites aren’t really “attracted” to an area. Any termites already present can easily make their way through the mulch to the timber in your home. When placed too close to your house, organic mulch can provide pests like termites with hidden opportunities to make their way into your home. 

In general, wood chip mulches won’t attract termites that are not already present in your area. However, you can improve your odds by periodically raking your mulch to provide aeration.

In a state of starvation, termites will feed on wood-based mulch, but the colony survival rate will sharply decline from a mulch diet. The real concern is that wood-based products and the gravel mulches hide termites more effectively and allow colonies to flourish undetected until the colony has severely damaged surrounding wood structures. 

The moist soil beneath mulches provides a convenient bridge from termite colonies in the garden to the house or other wooden structures. In some cases, gravel mulch retained more than moisture than wood mulch, providing termites with a stable and extremely favorable environment for infestation. 

The best way to decrease the risk of termites is to maintain long-term termite prevention and pest control with a pest management professional.

Tips For Mulching

When mulching:

– leave six inches of foundation showing between the ground and your home’s woodwork or siding. This is standard in most building codes to keep moisture from seeping into the wood. It’ll deter insects and rodents, too. 

– provide a “buffer zone,” a strip of bare dirt, of a foot or more wide between the mulch and your house foundation, particularly if you are using organic mulch to deter tunneling termites. It is best to keep this zone bare, but it can be filled in with small amounts of non-organic mulches, for aesthetic landscaping. It is important that the ground is graded away from the foundation of the home before placing any mulch. This enables water to run off away from the structure instead of toward it. 

– never layer any mulch more than three inches deep. This is particularly important for organic mulch. Anything deeper may never dry out and cause too much moisture in the soil. You don’t want the layer to be too shallow, though, or you’ll defeat the purpose of its use. 

– don’t water the house, keep the soil strip around the house dry and unattractive to termites. Don’t spray the walls of your home with sprinklers. 

Keep mulch dry. If your yard tends to stay wet, limit the mulch layer to three inches or less, and periodically rake it so it can dry out and aerate. 

  • Stay vigilant. Keep an eye on your home’s foundation, both indoors and outdoors, for signs of termites, especially above-ground tunneling structures. Watch for termite activity and damage inside your home, and address any problems immediately to limit any damage. 
  • Remove old mulch before adding fresh mulch.