Arnold's buzzworthy Fly Guy series gets another spinoff, this time co-starring Fly Girl. One day, Buzz invites Fly Guy to go to the zoo, inspired by a book about wild animals. Elsewhere, Liz invites her insect pal, Fly Girl. The human-fly pairs collide on their way with a "WHAP" (the flies) and a "WHUMP" (the humans). Once recovered, they decide to continue to their outing together. Buzz and Liz break off to go see the spider monkeys and naked mole rats, leaving Fly Guy and Fly Girl on their own. The two flies go looking for lunch, finding things that are "sticky," "slimy," "slippery," and "smelly." Their alliterative adventure culminates in a "scary" exhibit of "Creatures of the Night" (or, from their perspective, a "dark, dark cave"). "Gulpz" after "Gulpzie," the flies spook themselves silly as they meet each animal. They hide in a box for safety. But will their humans find them? Using fewer than 90 words and their variants--including some decoded "fly talk"--Arnold keeps the text easy to read. The quick pace, including some genuinely surprising page turns, ups the entertainment factor. It's unfortunate, however, that Fly Girl is presented with gender stereotypes: She's pink and wears a bow on one of her antennae. Both Buzz and Liz present White. (This book was reviewed digitally with 8.8-by-11.6-inch double-page spreads viewed at 25% of actual size.) Readers will buzz to it like flies to manure. (Early reader. 5-7) Copyright (c) Kirkus Reviews, used with permission.