My box hedge attacked by the defoliator caterpillar
The boxwood defoliator caterpillar, which I discovered to be called cydalima perspectalis (but the treacherous insect has a lot of synonyms of Latin origin) is a small calamity that I have seen with my own eyes. If you have such a hedge, and you are rightly proud of it, inspect it carefully and intervene as long as you are in time after reading this story.
Personally I have been taking care of one for years box hedge of about thirty meters that has been there for decades, beautiful, strong, luxuriant, of that bright dark green that in summer makes you cool to look at it. The hedge is not mine, it is in a vacation home, but it is as if I have adopted it (maybe because I don't have my own garden) and I feel like an artist when I take care of it, cut it, level it, comb it and model it to the way of the Italian gardens, as only with the good boxwood it can be done.
Then I saw her dry up, in fact I didn't even see her because when I greeted her a month ago she was as beautiful as ever and twenty days later (it happened in August) they called me that she was already brown. Brown mine box hedge? Yes, brown and dry that seems all dead, they told me, were it not for a few greenish flashes here and there and the roots that remain robust. The gardener, as far as he knows, said it was the caterpillar.
The word caterpillar it made me jump. Do you want to see that I knew? Do you want to see that those four fluffy cocoons I found in the branches in early July the last time I combed my boxwood were they really something weird? I had never seen them before, but as naïve as I am I thought about butterfly nests and I toyed with the idea: who knows how beautiful they will become after sleeping in my boxwood!
Stupid amateur, those were the larvae of caterpillar defoliator! Tender chrysalises waiting to turn into small sharp-toothed panzers capable indeed eager to burn a hedge of boxwood almost century-old thirty meters long. Having suspected without doing anything, having sensed the danger and not having at least gone on the internet to browse some blogs is a thought that does not give me peace, a kind of woodworm or rather a damn caterpillar. But it wasn't my fault.
Nor am I the only victim of this tragedy. When belatedly, I hope not entirely, I deepened the subject, I discovered that there are those who have been even more naive than me: an amateur garden enthusiast watered the box hedge and he saw multicolored fins fluttering away: how beautiful - he said - mine boxwood is the cradle of butterflies! Belle a c ...., wait in a month and you will find out who you rocked the cradle!
But now we come to us and what to do. The cydalima perspectalis, boxwood defoliator caterpillar, is a moth parasite of Asian origin which, after spreading to China, Korea and Japan, must one day have taken the plane and crossed the world. In Germany it was discovered in 2007, but woe betide if they told us, and in Italy it arrived for the first time in 2011 (that's why my boxwood had never got sick before) on Lake Como.
The tender killer must like the mild climate because my story also happened on the lake, the Maggiore one however, in the province of Verbania. Today the cydalima perspectalis it has become so infesting that they have added it to the Eppo Alert List of the EPPO (European and Mediterranean Plant Protecion Organization). The worst damage from us the boxwood defoliator caterpillar he made them in Lombardy.
How to locate and recognize the boxwood defoliator caterpillar? For this reason, I, who am a naive amateur, have read the indications released by the Phytopathological Laboratory of the Lombardy Region at the Minoprio Foundation. I found that the eggs are sheltered under the leaves (please check), at first they are pale yellow and when they swell they become dark.
The mature larvae of the boxwood defoliator caterpillar they reach 4 centimeters, they are well hidden in the vegetation (I only saw them because I was cutting with the hedge trimmer blade) and they feed on the leaves and buds of your hedge (in summer) before becoming beautiful butterflies and going elsewhere to lay more eggs, spreading the infestation. Do not hope that the arrival of the winter cold will be a cure: apart from the fact that there are no more harsh winters, the parasite resists the warmth in its cocoon and returns lively in spring.
The fight to boxwood defoliator caterpillar, and it is a tough fight, with repeated insecticide treatments in the juvenile stages of the parasite. Phytopathologists recommend killing active ingredients based on deltamethrin or cypermethrin or growth regulators registered for use on ornamental plants. A single treatment is not enough and monitoring must be continuous.
The gardener advised me to supplement the treatment with nitrogen-based fertilizers to nourish the leaves in particular. I'm trying to get mine back into effect box hedge, but if you still have one intact, act in advance keeping your eyes open with continuous checks: do not be surprised by boxwood defoliator caterpillar!
Now I advise you to read: Bacillus thuringiensis effective against the box borer
Bacillus thuringiensis Aizawai
Lepidoptera: plant parasites