I know that there is an authentic Hadith wherein the Prophet (may the Salah and Salam of Allah be upon him) prohibited the killing of ants. But, is it sinful to kill ants if a person finds too many of them in the house, especially in the kitchen? قتل النمل لدفع أذاه

All praise is due to Allah alone, and may the Salah and Salam of Allah be upon our Prophet Muhammad, his family and his companions. To answer your question, we say while seeking the success from Allah: Abdullah ibn `Abbas (may Allah be pleased with him and his father) narrated that the Prophet (may the Salah and Salam of Allah be upon him) prohibited the killing of four creatures: ants, bees, hoopoes, and sparrow-hawks. Reported by Abu Dawd (5267) This report indicates the prohibition of killing these creatures because of their benefits and lack of reason to kill them. However, if these creatures caused harm, then it is permissible to kill them to prevent their harm. This is based on the narration reported by al-Bukhari (3319) from Abu Hurairah (may Allah be pleased with him) who reported that the Prophet (may the Salah and Salam of Allah be upon him) said, "Once while one of the Prophets was taking a rest underneath a tree, an ant bit him. He, therefore, ordered that his luggage be taken away from underneath that tree and then ordered that the colony of the ants should be set on fire. Allah has revealed to him, "Would not it have been enough to only burn one ant (that bit you)'?” This report indicates that it is allowed to kill ants when they cause harm; otherwise it is prohibited. Allah knows best. Your brother, Khalid al-Mosleh   3/8/1427 H.