A butterfly with white wings outlined in dark: this is what the boxwood borer looks like in its adult stage
I'm back to writing about box borer, aka defoliator caterpillar, aka cydalima perspectalis, but this time to propose one biological struggle to infestation.
I state to the reader that my first meeting with the box borer dates back to the summer of 2013, as evidenced by my interventions on IdeeGreen, and since then I have been fighting and helping to fight against this infesting moth that is expanding and causing disasters.
Here I speak of biological struggle, but I repeat once again that if in September 2013 I had not faced the emergency with a strong dose of deltamethrin, which is not the most organic of the products, I would have lost the hedge and many greetings.
With repeated treatments of deltamethrin and a nitrogen-based fertilizer (as an adjuvant, I think it helped although I'm not sure) I saved from borer a box hedge which seemed 'burned' and a year later I brought it back almost as before.
The hedge I am talking about is located in Verbano Cusio Ossola near Intra, at about 900 meters above sea level (evidently the borer tolerates the fresh air well) and I think it was one of the first cases in that area, where there have been others. I'm talking about an ancient hedge, vigorous and robust, which had never fallen ill before.
The caterpillar defoliator cydalima perspectalis comes from Asia (apparently China) and was reported for the first time in Italy in 2011 (on Lake Como) after which it made a crescendo of disasters with a peak in the last summer of 2014. The mild winter l 'he favored as I had expected and I think the tropical humidity of the last few months has also helped him.
Having overcome the first fear (I assure those who are facing the problem that the hedges can be saved) I said that I am moving towards biological struggle focusing on a product that is not aggressive for the environment and less difficult for me who use it (maximum caution when using insecticide!) such as Bacillus Thuringiensis.
The box borer at the larval stage
The Bacillus Thuringiensis it is not new in the biological struggle to plant weeds and has also given good results against the fearsome pine processionary moth. There are three varieties of this spore-forming bacterium on the market, Kurstaki, Aizawai and Tenebrionis, but the one that works against box borer is the Kurstaki. Of the latter there are also seven different strains, but it seems that the strain is not decisive.
If you have trouble finding the commercial formulation of Bacillus Thuringiensis you can order it online like I did on Amazon. The Bacillus thuringiensis variety most effective against the box borer is the Aizawai.
Bacillus thuringiensis Aizawai from 500 gr
There biological struggle to box borer with the Bacillus Thuringiensis it must be set by providing 2-3 treatments a year and in any case following the easy instructions given on the product packaging. The bacterium acts selectively by paralyzing the digestive system of the larvae in the presence of basic pH (lepidoptera). In the presence of acid pH (higher organisms and man) the bacterium is instead ineffective, which makes the Bacillus Thuringiensis selective and safe.
I switched to biological struggle a few months after stopping deltamethrin treatments. But I'm doing it more as a maintenance and prevention than as a shock therapy since I haven't had any larvae in the hedge since May. It is working well but despite this, as I have already written in the light of the 'relapses', I always keep my guard up.
Here is the history of my battle against the box borer
Lepidoptera: plant parasites