Sori, 27 April 2021
There is a walk which my wife and I take in Liguria (calling it a hike would be a bit of a stretch), which brings us by easy stages to mid level on the hills dropping into the sea, leading us eventually to the small village of San Bernardo perched atop the old fishing port of Bogliasco, from where we can walk down to Bogliasco itself and catch a bus home (after, perhaps, an ice cream to reward us for the walking).
On the way, we pass a wide terrace, which stands out from the surrounding olive terraces and vegetable patches for the simple reason that it is terribly bare. The little grass it has is clipped to within an inch – what am I saying, a centimetre – of its life. This bareness is due to the terrace’s hosting a number of ruminants – a couple of donkeys and three-four sheep – which graze voraciously on any blade of grass that dares to raise its head.
Until a year or so ago, the terrace also used to host half a dozen magnificent palm trees – very old Canary Island date palms judging by their height and girth. Two years ago, we noticed a sign which proudly proclaimed that the palm trees were part of some EU-funded project, leading us to make cynical comments about the wasteful use of EU largesse. Last year, the palm trees were gone; the ruminants had the terrace to themselves. After more cynical comments about wastage of public monies, we began to wonder.
Liguria, like most Italian regions by the sea, has a large population of palm trees. The most common palm tree by far is the Canary Island date palm, and any self-respecting seaside resort will have at least one avenue lined with them, like this one in Taggia, in Liguria.
Many gardens in Liguria, both public and private, will also boast a palm tree or two. Other than the Canary Island date palm, it’s possible to spot, over a garden wall or tucked away in the corner of a park, a whole slew of different palm species: the true date palm, the Chinese windmill palm, the California fan palm, the Mexican fan palm, the Chilean wine palm, and more.
Now, the fact is that in the last year or so during our walks and hikes in Liguria we have been noticing many dead palm trees, either with their fronds dried up and drooping piteously, or with the fronds completely amputated leaving behind a forlorn blackened trunk.
A quick zip around the Internet has shown us that this Great Die-Off of Ligurian palm trees that we have been witnessing is due to this critter.
This is Rhynchophorus ferrugineus, known in English as the red palm weevil. It’s really a very pretty beetle, one which I would be proud to have pinned to the board of a beetles collection if I had such a thing.
But this pretty, pretty beetle has the unfortunate habit of laying its eggs at the base of palm tree fronds, from which larvae hatch, which then burrow down into the trunk to the root of the fronds and live off their lymph, killing them off in the process. The larvae pupate inside the trunks, and when they have metamorphosed into beetles, they crawl out and fly off to find mates and new palm trees to attack. This attack on the fronds is deadly because palm trees, unlike true trees, die when their crown of leaves are killed or are chopped off.
This beetle is originally from tropical Asia, where it attacks many species of palms. But the active international trade in palm trees has brought it to Italy, where it has been overjoyed to find a host of new palm trees to attack. Unfortunately for the palm trees, our beetle friend is not at all finicky about what palm trees it attacks. And it seems to have no complaints about the Italian climate either.
It’s the same old story of invasive species, a topic I’ve covered several times in these posts: the water hyacinth, the prickly pear, the Himalayan balsam, the Jerusalem artichoke, among others. I’m beginning to sound like a broken record, repeating myself over and over again (as I write this, it saddens me to think that only people over the age of 60 will know what I mean, because they might well have owned a vinyl record in their youth and seen how a scratch can lead to the needle jumping backwards and repeating the same piece of music over and over. But I digress.)
Of course, it’s not just Italy which has been attacked by this plague of red palm weevils. Everywhere along the southern rim of Europe, where the climate is mild enough to allow palms to grow, the beetle has arrived and is decimating palm populations. It’s also arrived in the Middle East and North Africa and is decimating their date palm groves.
In this case, there are large, and growing, economic costs attached to this plague – in Italy, palms are merely for show. In fact, I had come across anguished talk of this beetle a year or so ago, when doing some research on date palms for a project I’m involved with in Egypt (the largest producer of dates in the world, in case anyone is interested). It is only now that I have made the connection between the holocaust of palms in Italy and this other massacre of palms in North Africa.
A sighting of the beetle in California was reported back in 2010, but it turned out to be a false alarm. It’s only a matter of time, though, before the beetle arrives in the US, and many of those tall, thin, graceful palm trees my wife and I saw in LA will start dying.
And no other corner of the world where palm trees grow will be spared the red palm weevil’s scourge. Eventually, the pretty red beetle will arrive. We simply live in a world which is far too open to trade; if we and our goods move all around the world so will other species, some of which will turn out to be invasive in their new homes. Simple as that.
As if all this is not depressing enough, Italy’s palm trees are under further attack from another invasive species, a moth this time, which hails from Uruguay and central Argentina. Its formal name is Paysandisia archon, but it’s known in English as the palm moth or palm borer. It too is quite a handsome species.
It attacks palms in more or less the same way as the red palm weevil: it lays its eggs at the base of the palm fronds, the grubs once hatched burrow into the trunk to the root of the fronds, and then they proceed to suck the life out of the fronds. “Luckily” (if that term has any meaning here), this moth has a rather long life cycle, so it’s taking longer to spread through Italy’s palm populations than the red palm weevil (and so is getting less press). But it is spreading, under the radar. Like the red palm weevil, its tastes in palms are quite catholic, so none of the palm species in Italy are spared its attentions.
Of course, one could shrug one’s shoulders and point out that this beetle is wiping out plants that are not themselves natural to Italy but were brought here from somewhere else – a punishment for an earlier disregard of Nature’s ecosystems. Unfortunately, though, the beetle also seems to attack Italy’s one and only endemic species of palm, the dwarf fan palm.
As the name suggests and the photo shows, it’s a bit of a runt of a palm. It doesn’t grow more than 2 metres high, and it grows in clumps, so you can’t use it to line a stately avenue of some seaside resort. But it is actually from this part of the world, and it does have its niche and role to play in Italy’s ecosystems. Right now, the red palm weevil seems to prefer the other species of palm available to it in Italy, so it only occasionally attacks the dwarf fan palm. But imagine what will happen once the weevil has killed off most of the other types of palms around: very sensibly, it will turn to the next best thing to keep going, at which point the dwarf fan palm’s days will be numbered – if it hasn’t already disappeared, that is; contrary to the red palm weevil, the palm moth is very partial to the poor little Italian palm.
I’d like to end this post on a somewhat positive note, but right now it looks like we are losing the battle against weevil and moth. The classic modern response of spraying everything in sight with chemical insecticide is not only dangerous but it’s also not clear how well it works. And on top of that, it appears that the weevil at least is becoming resistant to chemical insecticides. Maybe pheromone traps could work. But maybe not. What I’m really nervous about is that some bright spark will go to tropical Asia (for the weevil) or Uruguay and central Argentina (for the moth) and bring back one of these pests’ natural predators, that the predators will be set free to attack weevil and moth, and that they will promptly attack some other easier target they find, thus becoming an invasive species in their own right – this is not science fiction, it’s happened before.
The best thing is just leave species where they are. We all have perfectly lovely local species. Let’s make our surroundings lovely with them and not with species we have brought from some other corner of the globe.