"In spite of the title, there is really only one giant spider, but we don't feel cheated because it's a dilly. It appears to be a Volkswagen covered with half a dozen bearskin rugs. Four spider legs operated by people crammed inside this VW spider, one assumes, have been attached to each side. The taillights double neatly as blinking red spider eyes. It is impossible to see such a budget conscious special effect without feeling a wave of admiration."
- Stephen King, Danse Macabre

"Veteran cast can't do much for this tacky horror opus filmed in Wisconsin."
- Leonard Maltin's Movie Guide

"There hasn't been a movie with special effects so bad since The Giant Claw [1957]. Different-sized spiders jump out of "black hole" and terrorize a small town. The big ones are stripped-down Volkswagens with legs and eyes added. Lots of laughs..."
- Michael Weldon, The Psychotronic Encyclopedia of Film

"This throwback to early science-fiction pictures such as Tarantula [1955] is moronic, plain and simple...The title is self-explanatory, except that the spider eggs are mistaken for diamonds by Wisconsin farmer Easton. Come on now, no one in the Midwest is that dumb."
- TV Guide

"...this film is clearly a displaced item from the fifties cycle of radiation (and such like) mutation movies...But, whereas the fifties films were at least a direct reflection of their times, this ineptly mounted offering has no such backdrop."
- The Encyclopedia of Science Fiction Movies, edited by Phil Hardy

"Bill Rebane's backyard wonder is a hilariously hokey throwback to the giant-monster flicks of the 50s, while taking its only pseudo-scientific conceit from the mid-70s trend of popular "black hole" theories, combining these two elements to create pure bad-movie heaven."
- Cavett Binion, AllMovie Guide

"This one you've gotta see for yourself; it's one of the all-time worst...The terrible moments are legion, mostly supplied by an embarrassed cast of washed-up has-beens and drive-in nobodies and some of the tackiest special effects on record.."
- James O'Neill, Terror on Tape

"Rebane jumbles comic strip with genuinely unsettling horror [with a] monumentally stilted script which provides many a chuckle."
- Time Out Film Guide

"It seems there's something about spiders, more than any other invertebrate, that fires the imaginations of really lousy filmmakers. Even with that in mind, however, The Giant Spider Invasion is something special. It isn't often that Alan Hale Jr. puts in the most credible performance in a movie, nor is it common to encounter a film that will offer up something as ludicrous as a black hole crash-landing in a cow pasture with a straight face. The most incredible thing of all, however, may be the simple fact that The Giant Spider Invasion was not by a long shot the worst movie Bill Rebane made."
- Scott Ashlin, 1000 Misspent Hours

It's apparent that nobody involved is sure how seriously to take the subject matter, so the script by actor Easton and Robert Huff tends to veer between cringeworthy humour and cringeworthy drama, often in the space of a few lines...Pretty much ridiculous from start to finish, The Giant Spider Invasion is really only valued for the unintentional humour it inspires.
- Graeme Clark, The Spinning Image

"Bill Rebane has a creative resume that would make most filmmakers choke on their own embarrassed bile...So it's no surprise then that this typical giant insect pic is so pathetic. Instead of focusing on the monsters for this movie, Rebane is too intrigued by the bevy of bilious characters he's created. Between the soiled back-brace hickness of Robert Easton's Dan Kester to the non-stop alcoholism of Leslie Parrish's Ev, the extra gravy heft of Alan Hale's portly policeman to Steve Brodie's human heart attack Dr. Vance, the individuals instilled with selling this insane insect shtick are downright depressing."
- Judge Bill Gibron, DVD Verdict

Compiled by David Kalat