Riva’s Horse Chestnuts Suffer from Leaf Miner Infestation, Authorities Seek Solutions

And this year, the early autumnal scene is present along the cool avenue that runs from viale Carducci to the Lido park. Not due to temperature (which remains very warm), but because of the unusual sight: countless withered leaves on the branches of horse chestnut trees, swayed by the wind and found at the feet of these majestic plants, forming a carpet that should be November-like but is instead seen during these hot days.

Sick. Once again this year, Riva’s horse chestnuts are sick. Some trees at Brolio are suffering, as well as others providing shade in private parks; but the most evident signs of their decline are on those — precisely — at the Lido. The culprit is a voracious little moth, identified by Slavic entomologists in 1983 as «cameraria ohridella», but commonly known as the «horse chestnut leaf miner».

The Horse Chestnut Leaf Miner and Its Effects

This tiny moth bores long galleries within the leaves, depositing its eggs inside. When the larvae emerge from their chrysalises, they find additional food within the leaf and ultimately devastate it. The leaves dry out and fall prematurely, the horse chestnuts become unsightly and pitiful, although they do not seem to be dying outright.

In Riva, as in Trentino, this malicious moth arrived in 1993. Likely imported from Macedonia via freight trucks carrying dry leaves. It has been observed that the spread of «cameraria» has followed major transportation routes so far.

Strategies for Combating the Leaf Miner

What can be done to fight it? Paolo Matteotti, a councilor overseeing urban greenery issues for the Comune, previously suggested burning fallen leaves to eliminate the chrysalises. But now, a new method has come from Milan — a city abundant with horse chestnut trees lining the streets — where gardeners are struggling with this moth problem.

It involves a targeted emergency treatment to be tested in spring: injections of insecticide directly into the tree trunks. If effective results are achieved in Milan, the Comune di Riva will likely adopt this strategy based on the Lombard experts’ experience.

The Importance of Horse Chestnuts and Final Thoughts

The horse chestnut trees are part of our landscape and enhance its beauty. If anyone discovers how to restore a proper «autumn» in the current context, it would be greatly appreciated.