[Foodstamp]

Yeah, they dissolve without magical leadership. Even so, they can lock up part of an army for several turns if you have one of the nymphs scripted to cast it.

If you have any passive defense in a province at all, you can use the spell defensively without them dissolving because of the Ent commander.

Try casting it with the Ancients, it should yield more permanent dragonflies and ants for the duration of the battle.

Either way, good catch. I am going to leave it as is because the both creatures are actually existing vanilla creatures and the issue only comes up when trying to use the spells aggressively with the Nymph in the early game. Later on you are probably expanding with atleast a Firbolg or two leading your forces, so the spell can be used more aggressively.