A little known insect rewilding project happened this week in Melbourne Australia. Several thousand Key’s Matchstick Grasshoppers were introduced into Royal Park. Rewilding is modern conservationWhy is animal conservation important? Animal conservation is important, because animals are the only mechanism to create biodiversity, which is the mechanism that creates a habitable planet for humans. Without animals, the energy from today’s plants (algae, trees, flowers etc) will eventually reach the atmosphere and ocean, much of it as carbon. The quantity of this plant-based waste is so More jargon meaning the introduction of animals with the intention of restoring ecosystemsHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how ecosystems function best, is when all components (including humans and other animals) can persist and live alongside each other for the longest time possible. Ecosystems are fuelled by the energy created by plants (primary producers) that convert the Sun's heat energy More. While we often associate these actions with big animals: beavers, wolves and so on, insects are just as important. In this article I take a look at three Australian grasshoppers and ask why they are important? What makes us love or hate different species and what’s the difference anyway? Aren’t all animals important in some way?
Why are grasshoppers important?
Grasshoppers and locusts are oft-maligned, especially by farmers as they can become a threat to our short-term food security. However, they are also an essential part of the fabric of any ecosystem.
To understand why they are important, we only need to consider how much vegetation they consume. Grasshoppers can eat 140kg of vegetation per hectare. As I’ve addressed previously, plant life isn’t an ecosystem without animals. At least not one that humans can inhabit. Plants would destabilise our biosphere, as they have in the past. The presence of grasshoppers can mean “1.4x more carbon is retained in plant biomass” (instead of being released into the ocean and atmosphere).
Why do we think animals are abundant now, or used to be, until recently? Aren’t they meant to be? Who are we to question the existence of any creature? Before we start castigating wildlife for the inconvenience it causes us, maybe we ought to consider the role they play. And whether any problems are our fault, not theirs.
The three species of grasshoppers we are about to talk about can each give us something different to think about.
Leichhardt’s Grasshopper
Leichhardt’s Grasshopper only feeds on Native Foxglove or Pityrodia bushes that grow best after cool season burns. By suppressing the growth in surrounding grasses, the bushes can compete for moisture. The grasshoppers then lay their eggs right next to the plants where their larva emerge to feed.
A single Leichhardt’s Grasshopper can live its whole life on the one plant. This makes both species especially prone to changes in climate and ecology. It also makes the bushes entirely dependent on the grasshoppers. Vegetation cannot diversify and remain succulent and healthy without their animal counterparts.
In 2009 I made this film with cameraman Nick Hayward. The late Max Davidson tells the story of how this one species became the focus of attempts to recreate traditional burning. Mt Borradaile is Aboriginal land where the First nations people maintain their strong connection-to-country. As Max explained:
“What the Leichhardt’s Grasshopper shows to me is what can happen if you want to preserve species. We have taken an animal from virtually on the edge of extinction. We look back and we see now that our whole bushland has changed.”
The late Max Davidson, Mt Borradaile, West Arnhem Land.
Key’s Matchstick Grasshopper
Key’s Matchstick Grasshopper is flightless so it can’t move very far. It would have once occurred throughout the states of Victoria and New South Wales (NSW), are, where it would have been a notable part of the biomassThe weight of living organisms. Biomass can be measured in relation to the amount of carbon, the dry weight (with all moisture removed) or living weight. In general it can be used to describe the volume of energy that is contained inside systems, as the size of animals relates to their metabolism and therefore, how much energy they contain and More of every piece of grassland.
In good habitat they are abundant, providing an important source of food for birds and insects, as well as promoting vegetation. Unfortunately, the traits that made it essential for soil health on a small-scale, also make it prone to impacts from agriculture. Traditional grassy woodland was converted for sheep grazing by European settlers and now the species has almost gone.
By the 1950s, scientists could only find them in old cemeteries: habitat islands protected from the ravages of farming. Since 2000 the NSW Threatened Species Scientific Committee reports they were only found in about 68km2. By then they were considered extinct in Victoria.
Grasshoppers and locusts are born as tiny larvae. In order to grow, they have to climb out of their hard outer skin and it can take several moults before they reach adult size. Meanwhile, they fulfil roles at different scales in the environment. For the Key’s Matchstick Grasshopper, even the adults are is only about 2cm. Unlike most other species, they are also flightless, so become locally important.
Remove local animals from an ecosystem and what happens? You get a build up of surplus nutrientsEnergy and nutrients are the same thing. Plants capture energy from the Sun and store it in chemicals, via the process of photosynthesis. The excess greenery and waste that plants create, contain chemicals that animals can eat, in order to build their own bodies and reproduce. When a chemical is used this way, we call it a nutrient. As we More – free energyThe energy of a system that is emitted as waste and is not part of ecosystem processes. There is always some free surplus energy as this creates the basis for evolution where new species exploit gaps in the ecosystem where free energy becomes available. Surplus energy can occur as a result of disruption or disturbance. When free surplus energy reaches More that destabilises ecosystems. And that is ideal for less specialist animals: migrant herbivores that swoop in when conditions are just right. These are conditions that enable the proliferation of locusts.
Spur-throated Locust
Locusts are another type of grasshopper. There is little difference except in the name. They are every bit as sophisticated as the insects described above, having evolved with the landscape over tens of thousands of years.
‘Locust’, though, is synonymous with ‘pest’ but that’s only because we have made them an inconvenience to farming. As far as nature is concerned they are simply responding to new conditions. Their only crime, if there is one, is to be fast-breeding and strong-flying. They hoover up surplus energy and respond to the imbalance in an ecosystem devoid of so many other animals. Surplus nutrients are also poured onto the land as fertiliser.
The Spur-throated Locust is one of three ‘plague’ locusts that occur in Australia. Even in the most pristine circumstances, one would expect locusts to swarm now and again. It is, after all, what they have evolved to do. Without locusts, ecosystems can quickly collapse.
To gauge how significant their impact is, however, let’s compare them with a large herbivore.
The scale and magnitude of grasshopper impact
Herds of 1.2 million African wildebeest weigh 216 million kilograms and consume as much as 4,500 tonnes of grass every day. That’s equivalent to about 4.2kg a day per animal, or 2.3% of their body weight. A grasshopper, however, can eat its own body weight each day and a single swarm of 27 million locusts would weigh in at about 50 million kilograms. This doesn’t decrease the amount of vegetation. Plant life bounces back even healthier, sometimes up to 18% more abundant.
These are figures that scare agriculturalists but look at it another way. What happens to the African ecosystem if you remove a quarter of a million wildebeest? No one would dare to dream doing that. Yet that’s what we think is necessary when locusts swarm.
The point is, locusts remain relatively benign, until the scale is tipped. If you look at the frequency of locust plagues for another species – Plague Locust – in Australia since the 1930s, they are increasing. It’s not that different to the increase in cyclones on the Great Barrier Reef, mouse plagues, or extreme weather events. Locusts aren’t becoming more abundant, the conditions that favour them, are becoming more frequent. The question we need to ask ourselves is what do we do next?
Grasshopper insect predators
Grasshoppers and locusts make up a big part of the diet of predatory animals including songbirds, lizards and snakes. They are protein-rich and many of the animals we take for granted – even seed-eating birds – will switch to insect prey at certain times of the year. This is especially when raising young. Without access to a plentiful insect-rich diet, many animals will fail to raise their offspring. Insectivorous birds, therefore, eat between 400-500 million tonnes of insect prey each year.
A collapse in farmland birds means many more larval locusts reach maturity. In the plains of North America, the wholesale destruction of prairie grasslands (along with their bird life), resulted in massive locust plagues within years.
Ironically, birds are often killed, by the very pesticides we use to try to ‘control’ insect plagues. Meanwhile, more surplus nutrientA substance that contains the raw materials for life. At a chemical level, these are contained inside compounds that are absorbed into the body and essential energy-containing molecules are extracted, so that energy can be transformed into other chemical processes that use the energy for living. More is poured onto the land as fertiliser each year. All the traditional approaches we use to respond to plagues simply make things worse.
Rewilding grasshopper country
Why are grasshoppers important?
Part of the solution to ecosystem collapse is to rebuild a country full of different types of grasshoppers, as well as the supporting cast of birds and other animals. It isn’t the number of animals that matters as much as the diversity and structure: to recreate balance. You can afford to have locusts if you have everything else. An ecosystem without insect rewilding by the likes of Key’s Matchstick Grasshopper, isn’t healthy. An ecosystem where you use poison everything will inevitably result in chaos(Of energy and ecosystems). Ecosystems are thermodynamically driven. Disorder occurs when energy dissipates and becomes more chaotic. For example, the release of hot air into the atmosphere results in that energy is freer to disperse (maximum entropy). The opposite is true when energy is locked into biological processes, when it is stored inside molecules (minimum entropy). Stability in ecosystems occurs More.
It will take a long time for insects like Key’s Matchstick Grasshopper to hop its way back across a continent without assistance. Leichhardt’s Grasshopper may never recover to previous levels of abundance. Locusts, meanwhile, are here to stay – and for good reason. Without them, we’d have a plague of something else.
None of these species however, are the singular key to insect rewilding but we can learn from each. The scale at which they impact our land could be staggering. We must stay mindful that this impact is a way to reset imbalance. A large effect on landscapes isn’t negative, it’s just inconvenient and messy, for a time. The worse things get, the more animals we need. There are many species like these grasshoppers ready to fix ecosystems, should we let them back in.
Imagine though, how simple insect rewilding could be. To restore ecosystem health, all we have to do is stand back, give animals some space, and let nature take over for a while.
