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For the past couple of weeks I have been testing ultrasonic electronic pest repeller. These things put out a 42 kHz +/- 20% and use about 5 watts. They were designed for indoor use. I cut up an old plastic bottle. Took a 20’ extension cord cut the receptacle end off. Melted a hole in the plastic lid of the bottle with the soldering iron. Ran the wire in the top and soldered it to the 110v plug prongs of the unit. Used silicon rubber to seal the wire with the top so that water would not run down the wire into the top of the bottle.

The instructions say the unit is effective in controlling mice, rats, roaches, fleas, flies, crickets, silverfish, waterbugs, moths, ants, and most other common pests. It covers about 750 square ft or 15’ radius. I mounted 2 units outside about 5’-6’ above the ground and about 10’ apart. I did this in stages of one week apart. The first unit was put up near 3 large spider webs and a series of 15 or more in the bushes near by. Just after turning it on I noticed no different behavior in the spiders. The next morning the three spider webs were gone and have stayed gone. The webs in the bushes had collected lots of leaves and debris (no spider to clean them). The second unit was put up 10’ away and the 2 large spider webs present disappeared over night. Flies and bees still visit the area. What it looks like to me is - the sound is just annoying enough to discourage taking up residency.

I plugged one of these things in within 4 ft of my two cats that were resting but not asleep. One became fascinated by the red flashing light or possibly the sound and knew something was going on. The other continued to rest for a while but then became interested in what the other was interested in. Neither one moved from the area. I ended the test. Decided if I hung it 5 or more ft in the air they would not be bothered if in the area. From my own experience I think the effective range outdoors is about 6 to 12 ft. I purchased 3 units for $17.99 from Harbor Fright tools item number 33626.

Offered by Mike.

I've never used them, but ultrasonic devices are very effective at driving insects away - all insects including the good ones. I see two problems with this. The first is that the majority of your vegetables rely on insects to pollinate. If the bees and other flying insects don't seem to be bothered, this might be a minor problem. The other problem is that if one or more of your devices fails suddenly (and you don't catch it right away) you will be inundated with insects almost immediately and the first ones, of course, will be the "bad" ones! (They always seem to know when there is a shortage of predator insects in a locale.)

Offered by Roger.

I live in a basement and have one of these wonderful little sonic devices. It works great. Absolutely no bugs, and my house used to be buggy. I put one of these on each floor and they are all gone. I think it really works and is a good idea to repel pests in a grow area. I am currently working on a small project that one can build with a few $ at radio shack to do the same thing. The circuit is very simple. Otherwise, they are only like $20 to buy, but I have only seen them mail order - not in stores.

Offered by Rob.

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