Water Bug in my Pool?

Today my son discovered one Beatle looking bug in our pool, SWIMMING! My husband caught it in his hand (ew, yuk I know). And we put it in a clear plastic container with rocks. My question is, if we have ONE in our pool will we start finding more,, how do I know if they laid eggs? It's HOT season and supposed to be 108 tomorrow I would hate to have bugs in our pool. My husband thinks if he heavily Chlorinates it,, that will prevent them from growing. I want to swim,, ALONE please help.