[3]) Its sexual development follows a seasonal cycle that affects the colony's migration and feeding habits, and vice versa.

L. japonica exhibits specialized predation, with prey consisting mainly of geophilomorph centipedes, a less reliable food source that also contributes to their high rate of nest migration.

[2][3] Like ants of genera Amblyopone and Proceratium,[3] the genus Leptanilla engages in larval hemolymph feeding (LHF), with the queen using no other form of sustenance.

Unlike any other ant, however, members of Leptanilla, including L. japonica, have evolved a specialized organ dubbed the “larval hemolymph tap” that reduces the damage LHF inflicts on the larvae.

[2] They have relatively large bodies covered in minute hairs and their hairless heads are quite small, a characteristic called stenocephaly;[4] this feature evolved to help large groups of larvae feed on one centipede body at once[5] Their mandibles also developed to help them feed; they are directed outwards and armed with sharp teeth, enabling the larvae to eat without assistance from the workers.

[4] The “tap” consists of a duct that connects to their hemolymph, with an opening surrounded by a small hairless area on the fourth abdominal segment.

Male ants of this species have been difficult to find in conjunction with workers and queens, and thus their behavior has not been observed and recorded as extensively as that of the females.

At the onset of spring, she enters physogastry, a phase in which her gaster greatly expands, while the first few larvae show signs of pupation.

[2] Leptanilla japonica navigate using a trail system marked with a gland secretion from their sternal side, though travel is disorganized and mostly individual.

The guard ants almost always assume the same position: they face the outside with their anterior end lifted, their forelegs raised, and their mandibles open.

Most of the time, the workers pull the centipede to the brood pile, with the colony occasionally moving towards the prey as well to meet somewhere in the middle.

She strokes a mature larva with her antennae, then holds the posterior end with all six legs, lying on her side and placing her lower mouthparts on the body.

She turns the body around, feeling with her mandibles until she finds the “larval hemolymph tap” in the fourth abdominal segment.

With so many individuals at the queen's disposal, severely damaging the larvae she feeds on would have a negligible negative impact on her reproductive fitness.

The queens of Leptanilla, on the other hand, cannot afford such a risk with colonies of only 100-200 individuals; an organ reducing the damage of LHF would be highly selected for in such a species.