[6][7] Ten undescribed species of this genus are said to be in Australia,[6][8] however molecular genetic analyses show that these taxa represent a separate lineage,[7] therefore their Australasian distribution is under debate.

[9] The genus Hemiandrus include the smallest wētā species, with adult individual body size no more than 7 millimetres,[8] and weighing less than a gram.

[12] The genus Hemiandrus shows sexual dimorphism between male and females in size, behaviour, and potentially abundance.

[18][7] Molecular dating evidence supports divergence of Anostostomatidae occurring at the Gondwanan breakup, with the species later dispersing across the Tasman sea.

In Hemiandrus, copulation differs from other wētā in the family Anostostomatidae, with the presence of the female’s secondary copulatory structure.

Once the spermatophore is deposited, the male detaches from the female, she bends her head toward her abdomen and grasps the spermatophylax.

[13] The spermatophylax has nutritional value and takes approximately an hour to eat, providing food for the female and ample time for sperm transfer to occur.

This incentivises large investment into the production of the spermatophylax from the male to increase the chances of successful copulation.

[30] Of the described species in this genus, half have a restricted range, but most are common and widespread, and are not thought to be endangered (as per the New Zealand Department of Conservation).