Leaf blowers kill insects and cause pollution and should not be used, the German government has said.
The country’s Ministry for the Environment stopped short of an outright ban, but issued new guidance in response to a request by a German Green Party MP.
The Ministry said that the devices should not be used unless they were “indispensable”.
The guidance added that the devices are “fatal to insects in the foliage”.
The government said: “There is a risk that small animals are absorbed or blown and thereby damaged.”
This year, German researchers warned that insect numbers are declining rapidly - with a drop in the number of species of up to one third in just 10 years.
Researchers from the Technical University of Munich (TUM) collected one million insects at 300 sites in Germany between 2008 and 2017.
They found that there were one-third fewer species than 10 years ago, both in forested areas and grassland.
Declines in insect numbers can have knock-on effects on bird, lizards and plants pollinated by insects.
In terms of insect biomass (the total weight of insects), the results were even more alarming, with a decline of 40% of insect biomass since 2008.
In grasslands, insect numbers dropped to one-third of their previous level.
Dr. Sebastian Seibold of TUM said: “Before our survey, it was unclear whether and to what extent forests were affected by the insect decline as well.
“The fact that a large part of all insect groups is actually affected has not been clear so far.”