Conservation Comment: Mole crickets could become extinct without anyone noticing

Mole crickets are found worldwide, and all have the same strange looking body arrangement. Photo / Colin Ogle

Late summer and early autumn are probably my favourite times of year. I enjoy the mild, calm twilight in the evenings and the sweet trilling of crickets.

Field crickets, like many invertebrates, have short life spans, or live for a long time as a grub or nymph, transforming into adults for just one summer. As the weather cools, many of the noisier and more visible insects around us disappear.

Much of the invertebrate life in our native ecosystems, however, carries on quietly and generally unseen. One of the most mysterious and weird of our invertebrates is the native mole cricket. Like the very familiar field cricket (Teleogryllus commodus) common to New Zealand and Australia, the mole cricket is ground dwelling and nocturnal. It inhabits burrows between 10-20cm deep and sometimes emerges during the night in wet weather. Occasionally people come across them, but they are rarely seen.

Mole crickets are found worldwide, and all have the same strange-looking body arrangement. Their head and thorax look curiously like a mole, and their front legs, used for digging, also resemble the front feet of a mole. The abdomen of most mole crickets look similar to a field cricket, with short wings used for singing as part of their courtship. The New Zealand native mole cricket differs, having no ears, no wings and making no sounds.

Unlike many insects, female mole crickets do not usually lay their eggs and abandon them. Instead, they create an underground chamber and guard their eggs until they hatch. In the insect world, care of young is usually seen among social insects such as ants and bees, rather than solitary insects.

Mole crickets were well known to Māori, who came across them while cultivating and named them honi. The first scientifically identified specimens were collected in 1915 at Aramoho in Whanganui. These were originally assumed to be the wingless nymphs of the European species Gryllotalpa vulgaris. In 1928, NB Tindale identified them as a unique native species, endemic to New Zealand. They have been given the scientific name Triamescaptor aotea, distinguishing them in a separate genus from all other mole crickets. Their closest relatives are two Australian Gryllotalpa species.

The native species is believed to be now restricted to the lower North Island, although it was formerly more widespread. As the mole cricket is ground-dwelling, agricultural cultivation is likely to have contributed to the decline of its range and population. Because the species is now uncommon, it is classified by the Department of Conservation as "at risk".

The honi, or mole cricket, is yet another example of a flightless, rare New Zealand species that could easily go extinct without anyone even noticing. Those of us who enjoy gardening need to keep an eye out for these odd little creatures. If you are lucky enough to find one, document your find using the i-naturalist website if you can, and make sure you do not carelessly squash one with your spade!

• Margie Beautrais is the educator at Whanganui Regional Museum.