CAMBRIDGE, NEW ZEALAND—In a cool, moist morning here, conservationist David Wallace and invertebrate ecologist Corinne Watts are standing outside the 16-hectare Warrenheip Reserve, which Wallace owns, discussing how to keep an insect fenced in.
New Zealand has plenty of invasive predators to keep out of the reserve. A 2.3-meter-high fence of mesh netting, a metal rim, and fine chicken wire—the wire also extends underground—blocks the rats, mice, cats, and weasels that would otherwise devastate the vulnerable native flora and fauna within. The reserve offers a glimpse of New Zealand’s past. Lush with kauri, tree ferns, and five-finger bushes that shelter iconic kiwi, it is a striking contrast from the surrounding pastureland. But one creature the reserve is designed to shelter keeps getting free: the massive, and endangered, native insect known as the Mahoenui giant weta (Deinacrida mahoenui).
In other countries, insect conservation might be an afterthought. But New Zealand’s weta, particularly the Mahoenui, are hard to overlook. In size and lifestyle, the giant weta is a mouse in cricket’s clothing. To be sure, it lacks the crowd appeal of other indigenous species, such as the kiwi: More than once, neighbors of Warrenheip have called to demand that escapees be removed from their homes. But weta, which means “god of ugly things” in the language of the indigenous Maori, likely played key roles in New Zealand’s original ecosystem. The mahogany-colored, fist-sized Mahoenui giant weta, for example, spends its nights foraging on leaves and hides from predators during the day, much like a mouse. Even its droppings are small and round like a mouse’s.
But it and other weta have been losing ground to invasive mammal predators until recently. Flightless and stingless, the odorous weta are easy prey for rats and even mice. “Their smell is so strong that any rodent just goes ‘Boom!’” says researcher Danny Thornburrow, who, like Watts, works at Landcare Research, a public-private research institute in Hamilton, New Zealand. As a result, several species of weta, like New Zealand’s flightless birds, have had brushes with extinction.