Lawn spiders are drawn to your yard for two main reasons: readily available shelter and an abundant food supply. They seek out dense vegetation, yard debris, and moist, dark areas for protection. Spiders primarily eat the insects that thrive in these same conditions, making them natural pest controllers. While they perform a beneficial ecological function, their presence can be alarming, prompting the need for effective control measures.
Identifying Common Lawn Spiders
Most spiders encountered in the lawn are harmless, with the two most common types being the Grass Spider and the Wolf Spider. The Grass Spider is a funnel-web weaver, identified by its two distinctively long, visible spinnerets, which are the silk-spinning organs at the rear of its abdomen. These spiders create non-sticky, sheet-like webs with a funnel-shaped retreat, often visible in the morning dew across the grass.
Wolf Spiders are robust, hairy, fast-moving hunters that do not build webs to catch prey. They are generally larger than Grass Spiders, ranging up to over an inch in body length, with a stout build suited for chasing prey. Their eye arrangement is a telltale sign, featuring two very large eyes set prominently above four smaller ones, giving them superior eyesight for hunting. Most lawn spiders are not a threat to human health, but if you suspect a dangerous species, caution and professional identification are advised.
Non-Chemical Control and Habitat Modification
The most effective long-term strategy for reducing spider populations involves making your lawn less hospitable to them and their food sources. Spiders seek out areas that offer dense cover and moisture, so altering these conditions can naturally drive them away. Cultural practices that promote a healthier, drier lawn are the first line of defense against these arachnids.
Maintaining an appropriate lawn height is one simple yet impactful modification, as tall, dense grass provides excellent cover for both spiders and the insects they eat. Regularly mowing your turf to the recommended height, typically between 2.5 and 3.5 inches, helps reduce this protective layer. Aeration and dethatching can also help by reducing the spongy layer of dead organic matter, or thatch, that lies just above the soil surface. A thick thatch layer holds moisture and creates a humid, dark environment for spiders and other small pests.
Clutter reduction removes prime spider real estate from your yard. Woodpiles, compost heaps, discarded planters, and piles of leaves or grass clippings should be moved away from the home’s foundation. Spiders use these items as shelter and anchor points for their webs. Additionally, consider adjusting your exterior lighting; bright white or blue lights attract flying insects, which in turn attract spiders. Switching to yellow or sodium vapor bulbs, which are less attractive to insects, can significantly reduce the spider’s food supply.
Direct Removal Methods
When prevention and habitat modification are not enough, direct treatments can be used to eliminate existing populations. For a non-toxic approach, food-grade Diatomaceous Earth (DE) is an effective mechanical killer. This fine powder is composed of fossilized aquatic organisms whose microscopic, sharp edges cut the waxy outer layer of the spider’s exoskeleton upon contact, leading to fatal dehydration.
DE must be applied as a very light, fine dusting to areas where spiders travel, and it loses effectiveness when wet, requiring reapplication after rain or irrigation. A simple, natural spray can also be prepared using water mixed with a few drops of peppermint, eucalyptus, or tea tree essential oil, along with a small amount of dish soap. Spiders dislike these strong odors, and the soap acts as a contact insecticide, breaking down the spider’s protective outer coating. Strong bursts of water from a hose can also be used to physically destroy webs and egg sacs, forcing spiders to relocate.
Commercial insecticides should be reserved for cases of severe or widespread infestation, typically when non-chemical methods have been exhausted. Products containing pyrethrins, which are fast-acting, natural compounds derived from chrysanthemum flowers, are a common choice. Pyrethrins work by disrupting the spider’s nervous system, causing paralysis and death, but they break down quickly in sunlight, offering a short residual effect. When using any chemical treatment, follow the label instructions exactly to minimize impact on the environment and beneficial insects. Always exercise caution, especially around pets and children, and avoid application if rain is expected, as runoff can carry the chemicals into waterways.