Moth Vacuum & Friends

Dj's gadget looks interesting. Those kind of things didn't work for me for mice in northern california - something else did (the Victor electronic mouse trap, which has a housing for peanut butter next to a battery and zapper) - but I can imagine them working for spiders.

The consensus of researchers who have actually investigated ultrasonic devices is these products do not effectively repel or eliminate pests from homes. In fact, in the 1980's the Federal Trade Commission (FTC) charged several companies with false advertising and required them to make refunds to customers. My guess is it is just a matter of time and the FTC will go after the makers of these other devices also.

Do ultrasonic pest repellers drive away pests?

No. Controlled studies have shown that ultrasonic pest repellers are ineffective at driving away wild rats and other pests. Specifically, ultrasound is no more effective than audible sound (Bomford and O'Brien 1990).

Ultrasonic collars do not drive fleas off of cats and dogs. Ultrasound does not drive away fleas or cause any change in flea activity patterns (Brown and Lewis 1991, Koehler et al. 1989). Ultrasonic cat collars have no effect on flea egg-laying, development of larvae, or flea mortality (Hinkel et al. 1990). Ultrasonic collars made no difference to the number of fleas on cats (Dryden et al. 1989).

Ultrasound does not keep wild animals away from roads. Ultrasonic devices did nothing to alter the behavior of moose (Muzzi and Bisset 1990), mule deer (Romin and Dalton 1992), or kangaroos (Bender 2001).

Ultrasonic devices are ineffective at repelling pests. Ultrasonic pest repellers do not repel cockroaches (Gold et al. 1984, Ballard et al. 1984), mosquitoes (Sylla and Kremsner 2000, Foster and Lutes 1985), white-tailed deer (Belant et al. 1998, Curtis et al. 1997), bats (Hurley and Fenton 1980), cats (Mills et al. 2000), starlings (Bomford 1990), pigeons (Griffiths 1988, Woronecki 1988), and many other bird species (Hamershock 1992).

Ultrasonic pest repellers do little to repel unwanted rodents. Rodents may be driven away for a few minutes or a few days, but they tend to return to their nesting and feeding areas even in the presence of ultrasound (Pierce 1993, Timm 1994). Ultrasound has not been shown to drive rodents out of buildings or to cause above-normal levels of mortality (Timm 1994).

Why don't ultrasonic pest repellers work?

Ultrasonic devices do not work because rodents rapidly become accustomed to repeated sounds (a process called habituation). Mice and rats learn that the ultrasound from the pest repeller isn't dangerous, so they gradually get used to it and return to their nesting and feeding areas.

In addition, ultrasound is quite weak and attenuates very rapidly with distance from the source (Lawrence and Simmons 1982). Half the energy of ultrasound produced by pest repellers is gone at 15 feet, and no energy remains at 30 feet. Ultrasound is therefore very short-range (Askham 1992).

I'm not going to answer your last question, H., because ultrasonic mosquito repellers all have one thing in common: none of them work. At all.

FTC Warns Manufacturers and Retailers of Ultrasonic Pest-control Devices

Staff of the Federal Trade Commission's Division of Enforcement today announced that they have sent warning letters to more than 60 manufacturers and retailers of ultrasonic pest-control devices, stating that efficacy claims about those products must be supported by scientific evidence. FTC staff reviewed print and catalog advertisements and conducted a "surf" of Internet sites marketing such devices. They found that many of the advertisements make explicit claims about the products' ability to eliminate rodents or repel insects. According to staff, these types of claims may not be in compliance with the FTC Act, which prohibits false and deceptive advertising.

(the Victor electronic mouse trap, which has a housing for peanut butter next to a battery and zapper)