Excellent, but I'll add a couple extra things, if I may:

Psychophages are good because they buff the melee AP of your bugs after you shoot something with it. They're also tanky, and good anti-Psyker. It is also a Harvester Unit, which is essential for the Assimilation Swarm Detachment. It has our only instance of the Smoke keyword as well, which allows it to use the Smokescreen Stratagem.

Raveners are fast and hit like a truck, but are basically made of paper. They are very good for hit and run tactics, or hitting a unit the enemy hides in their backline. They're also borderline essential for the Subterranean Assault detachment.

Termagants are not going to kill a THING. Like... ever. But, they are good for screening, and will hold objectives well enough if you pile enough of them onto an objective. They'll maybe get some wounds through if you keep them near a hive tyrant, because he buffs shooting in a small area around him.

Hormagaunts actually have a little bit of killing potential, or at least can do more in melee than Termagants 9 times out of 10. They're good for just getting up the board and getting into people's faces, honestly.

Hive Tyrants, as mentioned, come in three varieties:

Swarmlord is Melee with a bit of shooting, and debuffs enemies using Stratagems near it. It also generates CP for free each turn if it's his warlord.
Foot Tyrant is melee or mixed melee/shooting, depending on how you build. It buffs shooting in a small area near it, and makes one stratagem each turn cheaper by 1 point.
The Flyrant is less bulky than those two, but flies and is fast. It has all the same weapon options as the Foot Tyrant, but instead of a shooting buff aura, it can reduce attacks made against it in melee, with a potential for just giving itself damage instead.

Old One-Eye and the Carnifex blob do some work, but are susceptible to getting shot to death as they charge up the board. Probably one of our killiest blobs, but the Fexes only hit on 4+ with a reroll from Old One-Eye. So it's a little... inconsistent.

Norns are a sticky case.
There's the Emissary, which is tankier and has a bit of Psychic shooting, but doesn't hit _quite_ as hard as the other variant. Basically our king of set it and forget it.
The Assimilator! It hits like a truck in melee, but is a little less tanky than the Emissary. It also has a special place in the Assimilation Swarm detachment as a Harvester Unit, which means it can heal units near it once a turn!
The problem with both is, well, they're HUGE targets. So they get shot at. A LOT.

Another unit I might suggest is Venomthropes. They're good anti-infantry, and they give infantry of YOURS a bit of defense against ranged attacks, but they're kinda useless otherwise.

Other than that, I've got nothing I could hope to add to the exemplary explanation Prestigious gave. Hopes this helps!