Night Crawlers are fictional man-eating worms that appear in Double Down.
After Greg finds a bag of gummy worms in the pantry, he wants to make a movie with Rowley called "Night of the Night Crawlers", using the gummy worms as props for the Night Crawlers.
Night Crawlers are wormlike creatures that eat humans. There is also a King Night Crawler which is 500 feet tall which was planned to battle the mayor at the end of Night Of The Night Crawlers.
In night of the Night of the Night Crawlers 2, it is shown there are at least two ways to defeat a Night Crawler. The first is with worm repellent. The second is to freeze them. Some of their victims are The Husband and The Husband's Wife from Night of the Night Crawlers and Dave from Night of the Night Crawlers 2.