Mommy being Aggressive

My cat Pikachu is living with me and her 2 sons. Her oldest is almost 2 and her youngest is 1. Shes been really aggressive towards them lately and attacks them randomly. Its normally just a bite on the ear but Im wondering why. Her oldest son meows loudly alot and she normally goes after him then, but her youngest never meows

Are they all neutered/spayed? If not, that may account for her behavior.

They are scheduled to all get fixed soon but shes never been this aggresive

She is going to wind up pregnant again with all of the unspayed/unneutered cats you have.  She is acting out as she may be going into heat.  The boys are having issues as they want at her.  They all have too many hormones coursing through their bodies.  Please get them taken care of as soon as possible or you will have more cats than you know what to do with.