Lethocerus medius
Lethocerus medius is a species of giant [water bug] in the family Belostomatidae. It is found in Central America from northern Panama north throughout Mexico to southern Arizona, New Mexico, and Texas in the United States, and Cuba, Jamaica, the Cayman Islands, and the Bahamas.
They grow up to 49–58 mm for males and 62–63 mm of females.