In autumn this year I noticed a lot of grasshoppers around the place and their numbers continued to grow to point that driving for a few minutes in some areas nearby would see my van’s radiator clogged with them. Some sections of local roads became slippery through all the crushed critters.
These weren’t any ordinary grasshoppers, but locusts (aka “sky prawns” to the gastronomically adventurous).. which caught many of us by surprise.
Autumn’s arrival of locusts was a harbinger of what is expected to be Australia’s worst locust plague in 70 years this spring and summer – one of biblical proportions.
The locust threat has been so worrying that a government co-ordinated aerial spraying program on a massive scale is currently under way (and that’s a worry in itself in some respects).
For the last couple of weeks, I’ve been receiving SMS messages from PIRSA (Department of Primary Industries and Resources South Australia) daily informing me of spraying activities in the region and in the last week, up to 5 of these a day.
Luckily, my little patch of Australia has been free of major hatching activity, but I’m still likely to see “blow-in” locust swarms.
As destructive as the critters are, they are fascinating. As the hoppers emerge and start seeking feed, what are usually fairly solitary creatures experience a change in behavior due to their increased numbers and band together, forming almost a carpet on the ground. Hopper bands can reach densities of thousands of locusts per square yard. They will eat anything that is a certain shade of green and will even take a crack at non-plant materials such as green shadecloth and concrete painted green. However, during the autumn infestation, I noticed that most of the native trees and shrubs they didn’t seem to touch. Perhaps they’ve evolved to be unappetizing.
Once they have their wings, locust swarms can travel a hundred miles or more a night.
According to PIRSA, high density adult swarms can consist of over 50 locusts per square yard (a couple of hundred thousand an acre) and can munch through 20 tonnes of vegetation a day. In autumn, I was reading stories of farmers who had entire crops wiped out within 12 hours.
Once they have their wings, the battle is pretty much lost; so the government and landowners have been focusing on spraying the locusts during the hopper banding stage as there’s only a window of about 2 weeks between that stage and when the locusts take flight.
So far in South Australia, over 400 aerial targets have been hit and 448 hours of flying time have been accrued by five aircraft involved in spraying the hoppers. Aerial treatment to date has covered in excess of 1.2 million acres, just in my state. There has also been a substantial land based spraying effort.
Among the treatments being used is a product called Green Guard. Green Guard is based on a fungus called Metarhizium. The spores of the fungus are suspended in oil and then applied as an aerial spray. It targets grasshoppers, although bees can be impacted too. The disease caused by the fungus takes 10-14 days to kill a locust, so they still get to chomp through a fair bit between application and their demise.
I tried buying some Green Guard to have on standby just in case, but it’s as scarce as hen’s teeth. The supply crunch has its roots in an accident at the only manufacturing facility in Australia contaminating a batch and government agencies in this state and others buying all they can lay their hands on.
While the lack of Green Guard is frustrating, it was nice to see government agencies making an effort to use biopesticides, even though Green Guard is quite expensive stuff.
Not so green pesticides being used in the aerial battle against locusts are Fenitrothion (an organophosphate insecticide), Fipronil and Chlorpyrifos, another organophosphate insecticide. These kill more than just locusts and grasshoppers – they are broad spectrum.
The thought of my block being sprayed with organophosphates has sent shivers down my spine as the government has the right to spray without a landholder’s permission. In the aerial spraying program, Green Guard is being used only on organic farms or heritage areas and my patch is neither.
As I watch the various creatures on my patch going about their daily routines, with the eating of insects a part of that – I often wonder what other damage in being done in our 1.2 million acre poisoning spree. Insects play a vital role in ecosystems; not just as food for other creatures, but as pollinators and soil conditioners.
It’s a tough situation – we need the farmers to be able to bring in their crops, but perhaps other non-human residents of our state are at risk too through knock-on effects through spraying.
I really feel for our farmers – most have just been getting over record droughts followed by record floods in some parts.. and now this. I guess it would be easier for me to have a “kill ’em all” attitude towards the locusts if they were an introduced invader, but they have been a part of Australia since long before European settlement – they are a native creature. What role they play in the bigger picture in terms of our ecosystems (aside from being a food source), I’m not sure.
However, I also try to see things from the farmer’s perspective – spending all that time, money and effort in nurturing a crop, perhaps the first crop with any real promise for many years.. and then for it to disappear in a day. It’s not like you can put up netting over a 1,000 acre paddock.
With the non-availability of Green Guard and my legal (and neighborly) obligation to report and control the locusts had there been large hatchings, I’m just glad I haven’t had to resort to the poisons that are available to deal with the problem.. yet.