On Monday evening, Tuija Salmi from Helsinki received a call from a neighbor who had spotted two “strange trees” in Maunula, Helsinki.

The insects had emptied two large ash trees, leaving only leaf stalks and a few tufts of leaves in the tops.

Strait suspected there was some sting behind the destruction, but he did not know what.

- The larvae were no longer visible and there was no seith, he says.

The insects had eaten almost all the leaves of the ash tree.

Photo: Tuija Salmi / Reader's photo

Only tufts of leaves remained on the tops of the trees.

Photo: Tuija Salmi / Reader's photo

Researcher Tiina Ylioja from the Natural Resources Center of Finland (Luke) says that this is the Tomostethus nigritus leaf prick, which is part of the sawdust. He says it is no longer uncommon today for those stingrays to eat wood in this condition. Ylioja says that reports of the destruction of the stingray have now been made, especially in Helsinki and in various parts of southern Finland.

The Otokkatieto.fi website states that Tomostethus nigritus has spread strongly in Finland since 2015. It lays eggs on the buds of the ash in May, and the larvae hatch in early June. Once the leaves of the tree are eaten, the larvae fall to the ground to encapsulate.

- This native species is no longer considered endangered. However, the species is marked for reference in the laji.fi database, Ylioja says.

According to the Otokkatieto.fi website, the full-size larva is about 10 millimeters long and green in color.

Photo: Heikki Luoto / Bug Information

He speculates that there may be, at least in part, warm weather behind the increase in stingrays.

- One can speculate that since the rate of insect development is temperature dependent, then at least warm 2018, warm June 2019 and now warm June 2020 are favorable for the species. But the abundance was already observed in 2017, so to the peak of summer temperature alone, this abundance cannot be counted. The matter has not been clarified separately for this species, Ylioja states.

The adult Tomostethus is black in color.

Photo: Heikki Luoto / Bug Information

When the woodpeckers attack the ash tree and eat its leaves, the growth of the tree slows down, as the loss of leaves takes away the contact area from the tree and thus lowers carbon sequestration. Ylioja says the loss of growth is not harmful, but it is not known how many years the ash will last for the loss of leaves.

If you have tortures in your yard, you can catch them with adhesive papers wrapped around the tree.

- The application of ash to the base of trees has been tried and has prevented larvae that have fallen from trees or replaced trees from climbing back into the canopies.

- There are no approved chemical plant protection products or application techniques to control newly hatched larvae from the canopies, Ylioja says.

The trees eaten like this looked like Tuesday.

Photo: Tuija Salmi / Reader's photo

In order to get an overall picture of the eating of the species' ash, the damage they see can be reported to the Natural Resources Center with a deforestation report, even if it is not an actual deforestation.