Saimyōshō

The, also known as are demonic wasps of Naraku. They are used for retrieving Jewel shards, spying on various people, or to prevent Miroku from using his Kazaana, as their poison is deadly.

On the weak side for demons, many of them are killed by Inuyasha and his friends: their only strength is in their numbers. Saimyōshō resemble bees and, like Honeybees, they lose their stingers and die when they sting others.

They often accompany Naraku or his incarnations, but will obey Naraku's orders over those of one of his incarnations. They are seldom dangerous by themselves. In swarms, one unique ability they seem to possess is that they are capable of merging their bodies together to forge demon body parts: one instance is when they regenerated into an arm for Musō during his fight with Inuyasha.

Another one bonded together to form a severed ogre arm to attack Rin in the forest, during that time they also seem to be able to dissemble their merge form by whim.

Initially the Inuyasha's group refers to them simply calling. In the anime Inuyasha's group, only from episode 96 starts to call the Saimyōshō with their name, because they come to know from Sesshōmaru who was chasing two of them.

History
The Saimyōshō first appear in Naraku and Sesshōmaru Join Forces, when Naraku offers Sesshōmaru a hive of them so that he can neutralize Miroku while battling Inuyasha.

As Sango use her Wakizashi that the Saimyōshō use to be as a Shinidamachū, to lure Inuyasha's groups a trap.

Jaken was once poisoned by a Saimyōshō and he asked Rin to help him find a medicinal berry that would help him recover.

When Inuyasha storms Naraku's castle with the Red Tessaiga, Kagura is ordered to stop him from proceeding. She starts to fight Inuyasha, but goes easy on him, as she wants him to succeed in killing Naraku. When she sees the Saimyōshō watching her, she thinks to herself that they know she is losing on purpose, suggesting that the insects are quite intelligent.

It would also appear that Kanna has some connection to the wasps, as she can use them to show images in her mirror, like video-cameras. It is unknown whether she is simply able to use them, or if she is, in fact, their master, as it is not told exactly when Kanna was created and where the wasps come from. Naraku however ceases to use the Saimyōshō after her death. They live in nests or hives like regular wasps and bees, and are most often seen in forested areas, suggesting that they are herbivores, and try to avoid contact with humans.

During the Band of Seven arc, Naraku uses the Saimyōshō (and occasionally Kohaku) to relay orders to the un-dead mercenaries, like when they order The Band of Seven to flee battle because they would lose, or when they tell Bankotsu that Renkotsu betrayed and killed Jakotsu.

When Naraku discovers that Hakudōshi plans to usurp him, he dispels the child's barrier and calls the Saimyōshō away from him, allowing Miroku to suck up the incarnation and ultimately cause his death. And when Kanna's dead, Naraku no longer uses the Saimyōshō to poison Miroku's Wind Tunnel, opting instead to use a powerful miasma which is even more effective, though after the monk takes Yakurōdokusen's poison remedy, he no longer feels pain from the miasma.

But then the Saimyōshō has died by the time of the death of Kanna an the Mirror demon. Around the time that Magatsuhi first appears in the series, Naraku also ceases to use the insects for gathering intelligence, instead using Byakuya to do any espionage necessary, having no further need for the insects to spy for him.

Trivia

 * The Saimyōshō are based off the real life.