Fewest chromosomes in an insect

The smallest number of chromosomes possessed by any insect is one. This is the total number possessed by male specimens of the Australian jack jumper ant Myrmecia pilosula, because male ants are haploid (possessing only one chromosome from each chromosome pair present). The females of this particular species possess two chromosomes, because female ants are diploid (possessing both chromosomes from each chromosome pair present). So in females of this species, a single chromosome pair is present (thus two chromosomes in total); whereas in males of this species, only a single, unpaired chromosome is present in total. This is a highly aggressive species, whose sting contains potent venom. A person stung by a jack jumper ant commonly feels a sharp pain similar to an electric shock, which is followed by local swelling, reddening, fever, and the formation of a blister, but extra-sensitive victims can experience an anaphylactic attack.