Butterflies - the bad news, the good news

A whole post about butterflies and four photos without a butterfly in sight? Unfortunately, that's the point. I've hardly seen any this year.

Have you got butterflies in your gardens at the moment? When I was in London at the beginning of June I didn't see one, and here in Milan they are still very few and far between, despite the fact that there's plenty on the balcony to attract them. In the last week I've seen one or two fluttering around, but so far there's been no caterpillar damage at all - whereas by the beginning of June the hollyhock are usually lacy with holes and the caterpillarium is swarming with inhabitants munching their way through anything I've put in there.

Bad news. You may not like the caterpillars chomping at your prize flowers and veg, but they're an essential part of the ecosystem. Birds eat caterpillars, especially when they're raising their chicks, and the adult butterflies - apart from being a beautiful addition to the garden - are pollinators. Not the best maybe, but they play their part. No pollinators? No plants next year.

So why have they disappeared? I suspect it was the particularly hard winter we had. Here in Milan it went down to - 14°C one night. That's less than 7°F.

Butterflies either hibernate in the winter, or over-winter in chrysalis form. But I suspect that with temperatures that cold, a lot just didn't make it.

Which brings me to the good news. One type that I've not seen at all on the balcony this year is the dreaded Geranium Bronze Butterfly (Cacyreus Marshalli), which attacks both geraniums and pelargoniums and usually starts being a problem in May.

I'd decided not to bother with pelargoniums of any sort at all this year. Over the last couple of years I'd lost all those that I had to the GBB. It started slowly, with a couple being killed off each year, but then each year it got worse and worse, until not only had all the plants I'd had for years been destroyed but also any that I bought new would be dead within a couple of months. So no more, I said. The only way to solve the problem is not to buy them. And I didn't. Well, not for the house anyway. But for the office, I couldn't resist ...

And they're fine. No sign of public enemy number two (number one is red spider mite - and even that has not been quite so virulent as usual this year). They're thriving, keep bursting into flower and making me wish I'd bought more.

GBB is native of South Africa, so the idea that they couldn't survive the excessive cold does make sense. Hurray - perhaps that will check their advance through southern Europe a bit.

There is another possibility though. It could just be that they have hidden interests that entomologists have never suspected. And so they've all gone home to watch the football ...

Clean shaven caterpillars?

The boys are back. And I was wondering where they'd got to. Whereas by this time of year the caterpillarium is usually fully inhabited, this year I've not even had to think about it. Until last week that is.

Apart from the dreaded geranium bronze butterfly (cacyreus marshalli) we only really get two types of caterpillar on the balcony, which I suspect are cabbage white larvae. One is the one in the photo above. What is it? The colours are right for the large cabbage white, but it lacks the bristles that all the photos on the net seem to show. We do have a lot of white butterflies around, definitely of the Pieridae family, but the marking isn't quite that of the ones that I've seen illustrated. The other type of caterpillar is green with yellow markings, but doesn't seem to have been around this year at all. Again, it would appear to be very similar to the small Cabbage White, but without the bristles.

Butterflies do, however, exhibit regional variations so I suspect my identifications are correct and its just that Italian caterpillars are clean shaven. Italian men don't go much for beards either, so its obviously a cultural factor.

Anyway, I found the lad in the first photo, plus seven of his brothers and sisters, happily chomping away at an antirrhinum plant. Six are visible in the photo above - can you spot them? In comparison with last year's invasion, when they just about decimated the balcony, this lot are no problem. The plant had finished flowering and I can afford to lose it, so I've left them where they are.

The Geranium Bronze butterfly caterpillar is another matter however. These are definitely not clean shaven but short, squat and bristly. And a sort of odd lozenge shape. But by the time you see them it's too late. The young larva starts life by burrowing into the stems and eating the plant from the inside - see the tell-tale hole?

By the time it emerges as a full grown caterpillar the damage is done. The whole stem has been destroyed.

They're native to South Africa but arrived in Europe twenty years ago and are now widespread over southern Europe, while northern Europe is trying desperately to keep them out. The colder climates in the north may help to stop them spreading, but here they're a plague. I haven't got a plant that's not affected this year. There was an article in the paper the other day saying that geranium sales are down dramatically this year. The article was trying to put it down to the economic recession, but rather contradicted itself by saying that petunias and other annuals are holding their own. I wonder if it isn't just that people are changing away from geraniums because they just get too damaged and tatty. The butterflies are pretty little things, but give me the cabbage whites any day.

Explore some more ...

Cacyreus Marshalli, from the UK Department for the Environment, Food, and Rural Affairs

Cacyreus marshalli ... and company

May is the month the pests come back, and I've already had my first run-in with red spider mite. I think I won, but it's only the first battle in a war which will go on till the autumn, so I'm now checking daily and spraying regularly as a preventative measure with a mixture of onion, garlic, cloves and cayenne pepper which I found on a site called Bonsai Garden.

Other pests are also rampant and my caterpillarium now has a large number of residents chomping away. Unfortunately, I haven't always been able to move them in on time. I was in Tuscany for a couple of days last week and came back to find one of my chrysanthemums in an extremely sorry state - half eaten by voracious green caterpillars, and the other half infested by blackfly.

But the most worrying thing this year is the enormous number of geranium bronze butterfly (cacyreus marshalli) caterpillars that I've found. This is a pest that is rare so far in the UK and one that you're supposed to report officially if you see it - you can see photos and get details on the site for the Department for Environment, Food and Rural Affairs. But it transferred to southern Europe from Africa some years back, and in Italy is now well established. Not surprising, as it can go through 5 or 6 generations a year. It attacks pelargoniums, and though the mature caterpillars feed on the leaves and flowers and so are easy to spot and pick off, by then the damage has been done. There's an earlier stage where the newly hatched larvae bury into the stems and tunnel down through the plant, and that's what really does the damage. So there's no way of confining this one to the caterpillarium.

Acknowledgement : Photo of the geranium bronze butterfly provided under Creative Commons Licence by zigari44 via flickr