FILM: 'C.H.U.D.,' A TALE OF STRANGE CREATURES

In this summer when discarded alligators have been discovered maturing in local waterways, is it stretching urban paranoia too far to contemplate the existence of other strange creatures in our midst? Not for makers of horror films.

As evidence, take ''C.H.U.D.,'' yesterday's arrival at Loews State Twin and other theaters. If you believe the advertisements, C.H.U.D. stands for cannibalistic, humanoid underground dwellers, but it is one of the pleasant revelations of this enjoyable horror film that C.H.U.D. also stands for something else. Just what else is tied closely enough to a newsworthy local controversy to lend the proper measure of credibility to the plot, whose heroes are a photographer and a model; a police captain with a missing wife and a hippie who runs a soup kitchen for the homeless, especially for those who live in such underground dens as subway and sewer tunnels. The creatures can be counted among the victims, and the villain is that veteran heavy, the United States Government.

The absolute conviction with which Daniel Stern addresses the role of the hippie, A.J., goes a long way toward making ''C.H.U.D.'' work, and he receives a goodly measure of support from John Heard as the photographer and from Christopher Curry as the policeman. Helping matters are a knowing feel for the atmosphere of New York City, occasional flashes of wit in the script by Parnell Hall and commendable restraint (presumably by the director Douglas Cheek) in the administraition of the requisite doses of monsters.

''C.H.U.D.'' makes no pretension toward serious theses about government or the environment. It is meant to be light commercial entertainment, and in the category of horror films it stands as a praiseworthy effort.

The Cast C.H.U.D., directed by Douglas Cheek; screenplay by Parnell Hall; story by Shepard Abbott; director of photography, Peter Stein; produced by Andrew Bonime; released by New World Pictures. At Loews State, Broadway and 45th Street; Orpheum Twin, 86th Street and Third Avenue; 83d Street Quad, at Broadway; Gramercy, 23d Street between Park and Lexington Avenues, and other theaters. Running time: 88 minutes. This film is rated R. WITH: John Heard, Daniel Stern, Christopher Curry