The New Springtime

From back cover of Warner paperback May 1991:

AND THE HJJK SHALL INHERIT THE EARTH?

The People came forth from eons of ice to rebuild the world at Winter's End. But the horrifying insect hjjks -- led by an immortal telepathic Queen -- also wish to rule the New Springtime, and they are learned, united, and powerful, while the People are ignorant, tribal, and split into warring factions. Now the hjjks offer the People a "treaty," a vision of security that is seductive, beautiful... yet absolutely inhuman.

If the tribes refuse, the earth will run with genocidal blood. The People will be exterminated, or they will destroy a race infinitely old and wise. If the hjjks are accepted, the People will have survived the Winter -- only to lose their newfound humanity... Forever.

Synopsis from Open Library.