Fleas? You've got 'em collared. An electronic flea collar for dogs and cats emits an inaudible sound that fills the hateful little creatures with loathing and disgust. They should depart the vicinity within a few days after you put on the gadget, leaving you and Fideaux in peace. This water- resistant collar runs on small batteries. The sound it produces is way above pets' hearing range, so they won't be bothered by it. What will your dog do with the time that he formerly used to scratch furiously in every way possible? Read the newspaper, perhaps.

Electronic flea collar. $65. Friendship Hospital for Animals, 4105 Brandywine St. NW. 363-7300. LOVELY LINENS

Every once in a while something delicate, lacy and gorgeous is definitely called for in even the most tailored circles. You will never, for example, run across or want to run across a New Wave christening dress. This is where Elaine Wilmarth comes in. Wilmarth carries such antique linens as fancy top sheets, shams, tablecloths, guest towels and runners. Her period costumes and Victorian whites include dresses, petticoats, camisoles, wrappers, collars and children's clothes, with lace all over the place.

Linens and laces. Doily. $15. Tape lace purse. $45. Collar. $45. Elaine Wilmarth, 5715 Sir Galahad Rd., Glenn Dale, Md. 301/464-1567. MOMMY, WHAT CAN I DO?

Don't let the kid burrow too deeply into Smithsonian Surprises, a book by Sara D. Toney, before he finishes his geography homework. He'll never learn the capital of Sri Lanka that way. But he will learn how to make a trash bag fly, grow salt crystals, build a dinosaur theater and other useful skills. The educational activity book is based on Smithsonian resources, programs and objects. It should appeal to children six and over.

Book. $7.95. Museum Shop, Museum of Natural History, 10th Street and Constitution Avenue NW. 357- 1535. At other Smithsonian museum shops too. WOODEN WHEELIES

Strange but lovable, these Dona Dalton beasties. When did you last see a creature with black-winged torso, blue- striped legs, red wheels and a beady-eyed charge-ahead expression? Dalton also produces gentle sheep with garlands of posies around their necks, blue and white zebras, harassed hares poised to achieve racing speeds and other menagerie members. Roll one of these animals absent-mindedly back and forth across your desk while maintaining eye contact with an important client.

Creatures. The ones shown are $14 and $25. Moon, Blossoms and Snow, 225 Pennsylvania Ave. SE. 543- 8181.