So what happens when an ant colony with only one queen dies of natural or unnatural causes? The queen produces a variety of pheromones giving directions to the workers. One of the pheromones suppresses the ovary development of the workers, hence they don’t lay eggs. The main purpose of the queen is to lay eggs and to rule the activities of the colony. The workers nurse the offspring, forage and protect the colony. The queen lays two types of eggs; those that are unfertilized develop into males and the fertilized eggs that develop into female workers or potential new queens. In this case, when the queen dies, the workers can start to lay eggs. But since the workers have not been fertilized, these eggs will develop into males. These males will fly off once mature to mate. Therefore, this type of single queen colony normally cannot be sustained. However, there are different ant species in which workers are clonal and lay eggs that develop into females. The highest ranking worker will lay eggs while the others maintain the colony. If by chance this new egg layer dies then another worker will become the reproductive.
https://www.linkedin.com/pulse/what-happens-when-queen-ant-dies-randy-bilesky?published=t
http://www.delta-optimist.com/opinion/blogs/blog-what-happens-when-the-queen-ant-dies-1.2369591