Those white rings on tree branches that we had come to recognize are back, and this year they seem more numerous than usual. The protagonist, once again, is Takahashia japonica, the Asian cochineal that has been infesting the urban greenery of Northern Italy for some years and which has already made its appearance well in advance compared to previous seasons: the first reports date back to April 2026, weeks earlier than usual.
We talked about it last year, when the provinces of Milan, Monza and Varese were grappling with a rapidly expanding infestation and cottony filaments appeared more and more often on Milanese maples and liquidambar trees. Today the picture has worsened further.
Where reported in 2026
The diffusion has expanded significantly, and today the Lombardy Region records the presence of Takahashia in the provinces of Milan, Varese, Monza Brianza and Como. The cochineal of Asian origin, already identified in various areas of Lombardy, is being monitored by the Region to evaluate its spread and effects on greenery. Even in the Como area, reports are increasing exponentially.
In Busto Arsizio and Valle Olona, in particular, the last report dates back to May 1st and appeared on the Facebook page “Sei di Marnate se..”, which indicates the presence of the insect in via Diaz and via Varese, where the plants are already attacked and the infestation appears to be expanding.
In the town of Rho, the Municipality issued a statement on 4 May 2026 confirming that the area is also affected by the infestation this year. The Technical Office has recorded a significant number of reports, which generally arrive when the infestation is already in an advanced stage and the rings created by the insect on the plants are clearly visible, conditions for which decisive phytosanitary interventions are no longer feasible.
What the Lombardy Region says
The Phytosanitary Service of the Lombardy Region updated its technical note on the management of infestations in May 2025, available on the institutional website. The official position remains cautious: Takahashia japonica does not currently cause particular damage to the affected plants, even if in situations of particularly high populations copper desiccation may occur. There are no cases of deaths of public specimens attributable to this insect. The Region also clarifies that it is not a quarantine pest and that therefore no mandatory eradication or containment interventions are envisaged.
However, this does not mean that the problem can be ignored. The entomologist Mario Colombo, as reported by the newspaper La Provincia di Como, explains that when faced with a new species there is always an explosion phase, which in his opinion will continue into next year and then the downsizing phase will begin. The white that can be seen on the outside is wax, which has eggs inside: it is the ovisac of the mother cochineal which contains the juvenile forms of the insect, which then migrate with the wind to attack other plants.
The biological cycle: why May is the critical moment
In spring, towards the end of April and the beginning of May, the adult females produce the characteristic ovisacks. At the end of May-beginning of June the nymphs emerge from the eggs and migrate from the branches towards the leaves, settling on the lower pages and feeding on the sap; in autumn, before the leaves fall, the nymphs move to the branches to spend the winter. Acting now, before the eggs hatch, is the most effective time window. region
How to intervene (and what not to do)
Interventions are only possible in the initial stages of the infestation, through targeted removal of the affected branches. However, in most cases the reports arrive when colonization is already extensive, making pruning ineffective and potentially harmful to the plant.
There is no specific or non-specific product capable of killing insects, and even trying to intervene chemically risks causing more damage to the environment than to Takahashia. If you have an infested plant, the advice is to cut and burn the branches with heavy infestation, in order to reduce the risk of propagation.
To try to contain the parasite, the Municipality of Busto Arsizio has already taken a concrete step: on 24 April the Ecology office launched a biological control plan based on the release of coccinellids in different neighborhoods of the city, from the trees of Santa Croce in the centre, up to Sant’Edoardo and San Giuseppe. Ladybugs, natural predators of Takahashia, are used to contain the infestation without resorting to chemical pesticides.
How to report
The Phytosanitary Service of the Lombardy Region collects reports via the FitoDetective app. Alternatively, you can write to infofito@regione.lombardia.it attaching photographs of the infested plant and indicating the location. Reporting promptly, possibly before the rings are already fully formed, remains the only way to implement truly effective interventions.
