Q: In a catalogue I saw an electronic-sound device collar that is supposed to eradicate fleas. How effective is it? It's so expensive. Is it worth it?--N.B. A: Electronic sound devices are purported to drive insects away from animals with high-frequency sounds, but such claims are being contested by the federal government. Even if the collars do have some effect on fleas, they cannot end infestation because of the nature of the flea's life cycle. Flea eggs remain viable for six months and may hatch when the temperature rises above 78 degrees and the humidity increases by 50%. The larvae have a life span of a few days before the first of several pupal stages emerges. While fleas in those stages and in the adult phase are susceptible to insecticides (which come in a variety of forms: collars, sprays, lotions, shampoos and dips), eggs are resistant.
You can hope to alleviate your pet's discomfort by periodically removing fleas from the environment. Yet an animal allowed outdoors may bring in new populations of fleas after you de-flea it and the premises, so the process must be repeated.