I would like to preface this with the fact that this might be a intended feature but to me it appeared as a bug:
So when I fighting Dragonfly as Wigfrid, I was doing the normal fighting routine of a few blows and dodge and it was going good enough, and she went to go spawn larva. During this, I had freezed the larva with ice staffs so that they would no longer move before bursting. When she got to the last few, I used a panflute to put her to sleep, then I proceeded to freeze the rest of the larva. The problem was that when we were in the middle of fighting and the final larva burst, she didn't get enraged but instead went to go spawn more larva. Now this could have been written off if it happened once because maybe I had just did enough damage to make her spawn more, but she didn't stop and continued to spawn more and more larva after the last one died off. I did eventually find a workaround to where I had just tanked the damage until the larva spurted away but that was clearly not intentional to just tank damage like that for no good reason.
In short, Dragonfly went into a cycle of skipping enragment and spawning more larva after the last one died.
1) Fight Dragonfly until first larva armada is spitted out (for the most accurate experience, go with Wigfrid). 2) Freeze larva with ice staves as they spawn 3) When Dragonfly starts to go back to you, use a panflute to sleep her 4) Freeze rest of larva and continue the fight 5) Watch as doesn't get enraged after the final larva had died.