Strain : A word used to label some organisms (including insects) according to their geographical origin. For example, there are Bolivian and Puerto Rican strains of the wasp species Larra bicolor. Strains of the insect pathogen Beauveria bassiana likewise have been labelled. Strain does not mean the same thing as species, but is a term often used to indicate a subset of a species. However, a strain is not the same thing as a properly identified subspecies.