Alfred Russell Wallace, the Victorian era explorer and co-author of the theory of natural selection, did his most famous field work in the islands stretching from Malaysia to Australia. Among the trends he noted was a tendency toward gigantism on isolated islands. Just think of the cassowary or the elephant bird to put your mind’s eye on the phenomenon. Not all giants are that gigantic, of course, but that doesn’t make them any less so in proportion to their kind.

Take the weta, for example – a family of humongous flightless insects. Native only to the New Zealand archipelago, there are over 70 species of weta, 16 of which are under protection due to their reduced numbers resulting principally from habitat loss and over predation by introduced species.

Just how the wetas got so huge – some species are eight inches long – is not fully understood by scientists.  However, one widely held theory is that their gigantism resulted from the relative absence of mammalian predatory pressure, since other than bats, there weren’t many mammals in New Zealand originally.  But there really is no scientific evidence for this theory.  Whatever the various reasons, the result was a great variety of weta adapted to various habitats.  And weta are also important to the island ecosystem as prey for some native lizards, bats and birds.

Weta have been around a long time. They are one of the most ancient species living today, and fossil records show they have changed little in 190 million years. Unfortunately, islands are fragile, finite ecosystems and once the Polynesians arrived they transported the kiore, or Pacific rat, with them, and the rodents both competed with and actually preyed upon the passive insects. European explorers later brought the Norway rat, and since that time stoats and weasels, as well as introduced birds species that have killed and eaten the unsuspecting weta.

So, enter the invertebrate conservation experts including Dr. Greg Sherley of the New Zealand Department of Conservation, this team had to assess the situation and implement recovery plans to help stabilize the populations of the island nation’s endangered weta.  Dr. Sherley put it this way, “We knew at the beginning that it would take a variety of programs to protect the four families of weta – giant (or tree) weta, ground weta, cave weta, and the rarest of all, the tusked weta.  So, we made plans that included everything from captive-breeding to translocation and predator-removal.”

The conservation of such a group of animals takes some explaining, since much like rodents, they are not broadly endeared by New Zealanders. In appearance the weta are part cockroach and part giant cricket, with exaggeratedly long legs. Some species are predatory, others highly armored, some live in caves, some in trees, and some are quite dramatic in their appearance. The male tusked weta sports two ‘tusks’ with which they spar with other males or rasp together to ward off competitors. Weta are reclusive by day and scurry around the forest floor by night in search of their variety of food, from foliage to dead animals, to living prey such as other invertebrates. Not all weta are giants though. They range in size from over 70 grams to less than seven; the tiniest being the Nelson alpine weta.

Of the 16 weta species that are threatened, captive breeding is playing a role in their recovery. Over 100 Middle Island tusked weta were reared at the zoo in Auckland and were successfully released in nearby rodent-free habitat on Double Island and Red Mercury Island, in 2000. Now, that may not sound like a lot of insects, but the species was first discovered in 1995, when only 4 insects were located!  As Dr. Sherley put it, “The Middle Island tusked weta only survived on that one rodent-free island, so these disparate populations serve as backup and breeding stock for future releases on their native island.”

The Mahoenui giant weta was thought to be extinct until the early 1960s when an isolated colony was discovered among dense evergreen shrubs in the King Country region. 200 were translocated to Mahurangi Island where they are breeding free from predation.

“Depending upon your perspective, this tale of conservation and recovery efforts can say a lot about our priorities as a culture,” Dr. Sherley said. It is typically easy to rally support, both economic and political, for the protection of big and beautiful species. Just think of the bumper stickers you’ve seen concerning the protection of whales and eagles and wolves. Such species represent traits we admire and their protection seems like a noble cause.

Smaller creatures sometimes seem less so. Necessary, yet ignoble. However, the irony about the Earth’s living systems is that often the smaller an organism, the more vital it is. Among other things, that’s why there ARE so many small organisms. Insects, including the exaggerated wetas of New Zealand, are the most diverse of all known classes of creatures. And biologists recognize that there are likely many times their numbers of microorganisms. These microbes living in the soil play the most significant ecological role of any group of organisms on Earth because it is they who keep the system going.

So, before you let anyone tell you that saving weta or cockroaches is just going too far, remind them that though mega creatures like tigers and elephants are awe inspiring, it is in fact bugs and microbes that run the world. Comparatively, we mammals are but a speed bump in evolution.

And Dr. Sherley remains quite buoyant about the prospects for wetas and other New Zealand endangered species.  “Although most of the habitats in our country have been altered or destroyed by humans over the last few hundred years,” he said, “in New Zealand we have gotten over the highest hurdle first.  People generally do care a tremendous amount about these islands.  They are proud to live here and they recognize that this is a fragile and finite country.”