List of unnamed arthropods.
Amerind fly []

A fly on Kirok's face
This type of fly landed on Kirok's face while he and his newly-wed wife, Miramanee, were talking on the planet Amerind in 2268. (TOS: "The Paradise Syndrome")
Archer IV arthropods[]
Arachnid []

An Archer IV arachnid
The planet Archer IV contained a type of arachnid. (ENT: "Strange New World")
Firefly []

A firefly with Crewman Cutler
In the 22nd century, a species of firefly lived on the planet Archer IV.
One night in 2151, some of the fireflies were encountered there by a landing party from the NX-class starship Enterprise. The landing party included Crewman Cutler, who lightly waved one away while Ensign Travis Mayweather was telling a ghost story. The fireflies abruptly left the area, as Cutler noted. She and Commander Charles "Trip" Tucker jokingly commented on the possibility that either the story or the ghost in the tale had frightened away the insects, moments before a storm front approached. (ENT: "Strange New World")
Dakala bug []

A Dakalan bug
This "bug", as described by Commander Trip Tucker, which could "glow in the dark", was among the wildlife inhabiting the rogue planet Dakala. He further joked, "at least you can tell when they've crawled into your sleeping bag." (ENT: "Rogue Planet")
Dansk giant centipede []
In 2381, Ensign Brad Boimler was slated to go on a mission to Dansk, where he would attempt to "wrangle" giant centipedes while he was armed with a phaser rifle. However, Ensign Beckett Mariner ultimately got Boimler reassigned to accompany her to the Daystrom Institute, as she believed he was not ready to handle giant centipedes, which had poisonous pincers and mandibles. (LD: "Where Pleasant Fountains Lie")
Desert planet burrowing crab []

A burrowing crab
While stranded on a desert planet in 2381, Ensign Brad Boimler encountered crab-like creatures who could quickly burrow through the sand on the planet's surface. A group of these creatures attempted to carry off AGIMUS, but they were quickly stopped by Boimler, who kicked a few of them away, causing the rest to scatter. (LD: "Where Pleasant Fountains Lie")
Two of these creatures were among the lifeforms displayed at Narj's Miraculous Menagerarium. (LD: "I Have No Bones Yet I Must Flee")
Dominion planet bugs []
In 2370, while accompanying Nog and the Siskos on a trip to a planet in Dominion space, Quark complained about bugs being everywhere, saying that some had gotten into his jambalaya. Commander Sisko then asked what the problem was, as "[he] thought the Ferengis liked eating bugs." Quark then pointed out that they ate "Only certain bugs--Ferengi bugs." (DS9: "The Jem'Hadar")
Erabus Prime insect []
A type of insect lived on the planet Erabus Prime that was capable of transmitting a particularly nasty infection. (DS9: "Q-Less")
Hima insects []

Hima insects in 3188
At least two types of insects were forms of life native to the planet Hima in the 32nd century.
A land-dwelling insect, with a beige body and six legs, ate other insects. One of its prey was a blue flying insect.
In 3188, after catching its prey, the sounds of Michael Burnham and Cleveland Booker's ship entering the atmosphere caught the attention of a beige-bodied insect. (DIS: "That Hope Is You, Part 1")
Klingon food insect []

An alien invertebrate (upper left)
An insect-like creature of unknown origin was seen on a display in the Klingon restaurant on Deep Space 9. (DS9: "Playing God")
Lactra VII biting insect []
While on Lactra VII in 2269, Dr. Leonard McCoy attributed Lieutenant Nancy Randolph's malaria-type infection to an insect bite. (TAS: "The Eye of the Beholder")
Loracus Prime termites []

Termites native to Loracus Prime
Profiles of a number of termite species native to Loracus Prime were seen in the Handbook of Exobiology. (ENT: "Strange New World")
Martian insects []
Martian insects were forms of life that once existed on the planet Mars in the Sol system.
In 2364, images of the fossil remains were viewed by the Tkon Empire Portal 63 as it read through the entire database of the USS Enterprise-D. (TNG: "The Last Outpost")
Later that year, the same images were seen by Lore, as he was using the library computer of the Enterprise-D to learn more of the vessel and its customs. (TNG: "Datalore")
Rigel X insects []
Rigel X hosted multiple insect species.
Shortly after arriving on the planet in 2151, a large, flying insect landed on Commander Tucker's jacket. Its presence caused Tucker to twitch, prompting the insect to fly away.
Later, a species of butterfly was seen as part of a dance performance with female dancers, who consumed them. (ENT: "Broken Bow")