Insectoid Aliens

"It was no accident that they looked insectlike to human beings. Though their internal organs were now much more complex and specialized than any insects, and they had evolved an internal skeleton and shed most of the exoskeleton, their physical structure still echoed their ancestors, who could easily have been very much like Earth's ants. "But don't be fooled by that," said Graff. "It's just as meaningful to say that our ancestors could easily have been very much like squirrels.""

- Ender's Game

You've got Humanoid Aliens, and you've got Starfish Aliens. Somewhere in between are the Insectoid Aliens.

For some reason, authors like to model their aliens -- especially villain aliens -- after Earth bugs.

May or may not be related to a Horde of Alien Locusts.

Expect this trope to invoke a lot of Hive Mind and Bee People, and a philosophy of We Have Reserves and Attack Attack Attack. A Bug War will often (although not always) feature opponents that actually look like bugs.

Overlaps with Big Creepy Crawlies, though this trope deals specifically with extraterrestrial bugs.

Anime & Manga

 * Magical Girl Lyrical Nanoha Striker S introduces Lutecia, who has the ability to summon these. According to side materials, the giant Jiraiyo beetles come from the mountainous region of an uninhabited planet, while the insectoid Kaiju Hakutenou is a rare creature from a planet outside TSAB jurisdiction.
 * The Vajra from Macross Frontier can not only survive in space, but are perfectly capable of both fold communication and fold travel.

Comic Books

 * The Zylons from DC Comics' Star Raiders graphic novel.
 * The Antarenes, from Superworld Comics, look like large green ants. They attempted to push the Earth into the sun and replace it with their own planet.

Eastern Animation

 * Freakish giant hornets in space attack in Time Masters, the Rene Laloux / Moebius film.

Film

 * The Prawns from District 9 are Humanoid Aliens with an insectoid slant.
 * The main villain from the first Men in Black film is a twenty foot long cockroach from outer space.
 * The titular aliens from the Alien films aren't strictly insectoid, but they do have an ant-like society.
 * The Martians in Five Million Years to Earth (AKA Quatermass and the Pit) looked like large locusts.
 * The villains of Godzilla vs. Gigan are cockroaches from space.
 * The Geonosians in Star Wars Episode II: Attack of the Clones. The Star Wars Expanded Universe offers up many more examples.
 * This is what  from Team America World Police is shown to be at the end of the film.
 * The Arachnids from Starship Troopers. They come in various shapes and sizes too - the common "infantry", so to speak, consists of pretty large (taller than humans, but not by much), four-legged, shrieking horrors, but there are also giant fire-breathing beetles, dragonfly-wasp-fly-like flyers big enough to grab and lift a man from the ground and, best of all, enormous brain-eaters that resemble bloated larvae. They seem to have a hive mind system.
 * The aliens in Alien Apocalypse (2005) are locust-like and feed on trees.

Literature

 * The Bugs from Starship Troopers is an early example of this trope.
 * The Formics from Ender's Game are insectlike with a Hive Mind. They are also nicknamed "Buggers".
 * The "Wormface" aliens in Robert A. Heinlein's YA novel Have Space Suit Will Travel.
 * Several races in the Star Trek Novel Verse. Most are highly conservative cultures, and range from the peaceful Nasat, who resemble giant pillbugs and are known for their desire to avoid conflict (see Starfleet Corps of Engineers in particular), through the Orishans, to the hostile Cheka, who resemble spiders. There are also Kaferians, Jarada and the wasp-race in the first Starfleet Corps of Engineers story.
 * The thranx of the Humanx Commonwealth series by Alan Dean Foster (see the page pic). As the name would imply, humans and thranx are allies.
 * The Groaci of Retief are vaguely insectile.
 * The Taxxons and (to some extent) the Helmacrons from Animorphs.
 * And the Skrit Na larval state-Ax said it looked like a giant cockroach.
 * Also, the Nesk in "In the Time of Dinosaurs".
 * The Mi-Go from HP Lovecraft's Cthulhu Mythos can fit, although in their introductory story "The Whisperer in Darkness", they are more commonly described as crustaceans.

Live-Action TV

 * There's an alien like this in the Doctor Who episode "Utopia".
 * A different species, resembling humanoid flies appear in "Planet of the Dead".
 * One of the Xindi races in Star Trek Enterprise.
 * A crime lord in the early seasons of Babylon 5 is basically a sentient praying mantis. There are also the Shadows, which basically look like human-sized, black, spiky spider people, and the Gaim (who underneath their environmental suits look like giant ants).
 * A number of the less silly aliens from Power Rangers tend towards this, although being played by men in suits, they're usually still bipedal. Most notably are the Barillian Bugs that wiped out most of Andros' homeworld of KO-35 from Power Rangers in Space. They are The Virus- get stung by one, and you slowly turn into one.
 * The Worms from Kamen Rider Kabuto.
 * The Reetou, from the Stargate Verse, have an insectoid structure.

Tabletop Games

 * One of the races that the Tau are allied with in the Warhammer 40,000 universe are the insectoid Vespid. The Tyranids are also heavily modeled after Earth insects, having six limbs and chitinous armor (though thankfully, no Earth insect we know of has More Teeth Than the Osmond Family or Combat Tentacles).
 * In Starfire, the enemy aliens-bent-on-genocide during the Fourth Interstellar War are called the Arachnids. I'll give you one guess as to what they look like.

Video Games

 * The late 90s Insectoids line of Lego sets featured a planet populated by various giant insect species - therefore, the ships of the planet's colonists all had deliberately bug-like features, as a means of disguise from the local wildlife.
 * The Drudge from The Conduit and Conduit 2
 * Yars Revenge. They're actually originally Earth insects that became mutated into alien creatures.
 * One of the races of the Covenant from the Halo games are Drones, insectoid flying aliens.
 * Half Life 2 has Antlions, which are (presumably) from Xen.
 * The rachni from Mass Effect. Also, from the second game, the Collectors.
 * Conquest Frontier Wars: The mantis.
 * The Space Pirates from Metroid seem to switch between this and humanoid crustaceans but are really more fleshy or scaled creatures that wear insectoid armor. There are plenty of straight examples of course, like the Ki-Hunters and Kanden.
 * The Hivers from Sword of the Stars.
 * The Scrin
 * The Mandibugs and their leader Bugaboom from Super Mario Galaxy. Averted with the bees, however.
 * Starcraft: Zerg. 'nuff said.
 * The Odarites from Otherspace, ant-wasp things forced into a mafia-like corporate structure from birth.
 * Earthbound: Buzz Buzz.
 * Klackons in the Master of Orion games. Tachidi in the third.

Web Original

 * The Grex of the Swarm On the Somme series on Alternate History Dot Com.
 * The trolls from Homestuck look like ordinary humans with horns, yellow eyes, and grey skin, but they are apparently more akin to insects by way of Bizarre Alien Biology. They resemble large grubs with humanoid heads when first born, then gradually become more human-like as they grow up, and there's some Expospeak coming from them about internal body parts that would make more sense on an insect.
 * The bug aliens in Starship.

Western Animation

 * In Space Ghost, Zorak (pictured above) was a giant praying mantis.
 * The Irkens from Invader Zim look sort of like a cross between Insectoid Aliens and Lizard Folk.
 * Ben 10 can turn into Stinkfly and Eatle.