Spiders can be nuisance pests in homes, making messy webs and occasionally biting. Many homeowners look for ways to deter spiders from entering and living in their houses. One type of product marketed for spider control are plug in ultrasonic or electronic repellents that claim to emit frequencies that drive spiders away. But do these devices really work at keeping spiders out of homes?
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How plug in repellents are supposed to work
Plug in spider repellents are electronic devices that are plugged into standard electrical outlets in the home. They claim to emit ultrasonic sound waves or electromagnetic fields that are unpleasant or irritating to spiders, causing them to avoid rooms where the repellents are used. Manufacturers claim that the imperceptible high-frequency sounds or electromagnetic frequencies trigger a natural aversion or disorientation in spiders, essentially driving them away or preventing them from building webs and nesting in treated rooms. Theoretically, using enough of the plug in repellents to treat key areas in a home could make the environment inhospitable to spiders and reduce spider populations without the use of insecticides.
Effectiveness is highly debated
There is considerable debate among pest control experts about whether these plug in devices actually repel spiders as claimed. Much of the skepticism stems from the fact that there is little scientific evidence that they really work. Some reasons experts believe ultrasonic and electromagnetic repellents may not be effective include:
– Spiders lack structures to hear airborne sounds and perceive electromagnetic fields. Most spiders have simple eyes and rely more on touch, vibration and chemical senses to perceive their environment. They do not appear to have sensory organs to detect the signals emitted by most plug in repellents. This means the spiders likely cannot even perceive the presence of the repellents.
– Signals do not travel far enough. Ultrasonic and electromagnetic signals quickly weaken over distance. The frequencies emitted by most small plug in devices likely decay to undetectable levels just a few feet from the device. Therefore, the signals would only cover a very small area in a room. Several units spread throughout a room would likely be needed for there to be any chance of adequate coverage.
– Spiders continue to be found in homes using repellents. Many homeowners report still finding spiders, webs and egg sacs in rooms treated with plug in repellents. The continued presence of spiders indicates the devices do not create an environment that spiders strongly avoid.
Limited research on efficacy
There has been little scientific research specifically testing whether plug in ultrasonic or electromagnetic repellents effectively deter spiders. However, a few small studies provide some insights:
– One lab study exposed house spiders to an electromagnetic repellent under controlled conditions. The researchers found no effect on spider movement or distribution in containers in the presence of the electromagnetic fields.
– A field study tested four different ultrasonic pest repellent devices in rooms with confirmed spider populations. Over a 10 week period, there was no noticeable decrease in occupied spider webs in the rooms with active repellent devices compared to control rooms.
– A study reviewing data from a pest control company found no difference in spider populations reported by customers using ultrasonic devices compared to those not using them over a 9 month period.
The limited research to date indicates the plug in repellents do not have a measurable effect at driving away or reducing spider populations within homes. But more controlled studies are still needed.
Potential reasons repellents may not work well
There are several factors that likely contribute to the questionable effectiveness of plug in spider repellents:
1. Limited range of frequencies and intensities
The small plug in devices only emit a narrow range of ultrasonic frequencies and electromagnetic fields. There is likely a lot of natural variation in what frequencies and intensities actually deter different spider species, but the limited outputs of most repellents probably do not cover enough of this range to affect many common household spiders.
2. Difficulty dispersing signals throughout entire room
It is challenging for the localized signals from small plug in devices to spread evenly throughout a whole room at intensities that might have an effect. Nearby furniture, uneven wall surfaces and objects can create signaling dead zones that spiders could occupy while avoiding stronger signal areas. Multiple repellents spread throughout rooms could help address this issue.
3. Spiders are often unseen or inaccessible
Spiders often reside out of sight in cracks, crevices, under furniture and in wall voids where signals from plug in repellents likely do not reach very well. These hidden populations could remain unaffected by the repellents and continue to breed and emerge into rooms.
4. Other favorable factors may override repellency
Even if the signals bother spiders, other factors like abundant prey, favorable climate and suitable nesting sites may override a weak repellency effect and cause the spiders to continue occupying an area. Any repellency impact requires levels high enough to strongly deter spiders relative to other favorability factors.
5. Adaptation or habituation is possible
Some research indicates insects can adapt to ultrasonic and electromagnetic signals over time, becoming desensitized and no longer repelled by them. Long term exposure may cause spiders to habituate to the once annoying signals, much like people can adapt to background noises. This could gradually reduce any repellency effect on resident spider populations.
Use of repellents should be supplemented with other tactics
The lack of strong evidence showing plug in repellents alone effectively reduce spider populations means they should not be solely relied upon for spider control. Instead, incorporating the devices into an integrated pest management (IPM) approach combining multiple tactics will provide the best results:
– Remove spider web nests, egg sacs and block access points into the home to eliminate current infestations and deter re-entry. Thorough vacuuming and sealing off cracks limits the onsite spider population.
– Reduce environmental appeal through improved sanitation and clutter control. Good housekeeping lessens food sources like insects that attract spiders. Manage moisture sources spiders require.
– Employ repellents to supplement the above tactics. Though not proven highly effective alone, the devices may provide some additional repellent impact when combined with exclusion, sanitation and population removal methods.
– Monitor and directly remove any spiders observed. Traps can also capture wandering spiders. Ongoing inspection and removal keeps populations from rebounding as effectively.
An IPM approach uses multiple complementary tactics including repellents which is more likely to successfully manage spiders than simply relying on the repellents alone. Always read and follow label directions if using any chemical insecticides for spiders in addition to repellents.
Conclusion
Plug in ultrasonic and electromagnetic spider repellents available to consumers have not been conclusively proven to effectively drive away or eliminate spiders. Their effectiveness claims rely more on anecdotal reports than scientific testing. The limited research to date indicates they likely do not repel spiders well enough when used alone to significantly reduce indoor spider populations. However, when combined with other pest management tactics like sanitation, exclusion and trapping as part of an integrated approach, the devices may provide supplemental repellent effects. Consumers should not rely just on plug in repellents to solve a spider infestation but rather incorporate them into a multifaceted control strategy for best results. Anyone with severe arachnophobia or serious spider infestations may want to have a professional pest control company evaluate and treat their home.