The movie does a pretty good job of making a cute little goldfinch and its chicks absolutely terrifying. While a mother bird feeding her children obviously isn't scary, Hopper's Family-Unfriendly Death shows how horrifying it would be if you were a bug.
The sound the bird makes; they did a convincing job of depicting what birdsong must sound like from a bug's perspective, because the noises she makes would be right at home in Jurassic Park.
Hopper in his first appearance, and some appearances afterwards. Especially the scene where he kills a few of his henchmen with a bored look on his face.
The bar at the insect city has both human blood and Black Flag (an insecticide) on tap.
Hopper when he's attempting to strangle Flik: "I'll get more grasshoppers and be back next season. But you won't!!!"
Hopper menacingly approaching Flik, fire burning in the background, with the greatest murder-face on a family movie villain.
The theme park attraction based on the movie at the Disney Theme Parks, It's Tough To Be A Bug.
Grasshoppers trudging out of the mist with no music, only the howling wind.
This movie manages to make a rainstorm pretty terrifying. After all, normal raindrops hit the ground like watery napalm.
The entire sequence at the end of the movie, beginning with the rain. What is a normal and perfectly harmless occurrence for we humans is amplified into a nightmarish and regular disaster for all bug kind. Amidst the chaos, Hopper still manages to spot Flik, and with a furious roar, lunges at him (see above image), and snatches him and flies off. Flik's friends from the circus try to come to the rescue, but their rescue attempts are all foiled. (Admittedly, the incident where Hopper lost one of his antennae is pretty funny.) Not even Princess Atta can keep Hopper away for too long, and his final death, albeit very karmic, in and of itself was very unsettling.
"They come. They eat. They leave." This line could be a tagline for a horror film.