That'll work.
Should we adjust the primary queen's CR, or do we think the flop and additional HD keep her at CR 4? I'm going to say yes --- an un-informed 4th-level party could easily get a fighter pinned by the flop.
Ready for the hive information?
She also loses the claw attack and her speed. Of course, she gains the flop. I can see CR +2 if you think Flop is equivalent to being able to move and claw, but I'm not entirely convinced. As you say, it would be pretty easy to stay back and used ranged attacks. In other words, I doubt a party is going to get too many people pinned.
Shall we say CR 5 for the time being?
Let's see... the stat block in question would look something like:
Isopterite Primary Queen (Colossal Monstrous Humanoid; Hit Dice: 16d8+128 (136 hp); Init: –1; Speed: 0 ft.; AC: 15 (–8 size, –1 Dex, +14 natural), touch 1, flat-footed 15; Base Attack/Grapple: +16/+46; Attack: —; Full Attack: —; Space/Reach: 30 ft./ 20 ft.; Special Attacks: Flop [DC 26, then either crush for 2d12+21 damage or Bull Rush with +20 check modifier]; Special Qualities: Darkvision 60 ft., hive mind; Saves: Fort +15, Ref +9, Will +13; Abilities: Str 39, Dex 8, Con 26, Int 4, Wis 13, Cha 11; Skills: Knowledge (geography) +5, Knowledge (history) +5, Knowledge (local) +6, Knowledge (nature) +6; Feats: Great Fortitude, Iron Will, Open-Minded (×3), Snatch; CR: 5)
With the bite attack and Flop, I'd be ok with CR 6. It's not an exact science.![]()
We're agreed then. I'll try to remember to update the Working Draft once I'm finished working today.
OK, I think the monster stats look done. Ready for the hive information?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.