The German government has warned against the use of leaf blowers over concerns for insects and the environment.
Germany's Ministry for the Environment said leaf blowers were too loud, polluted the air and posed a fatal threat to insects.
The ministry issued the guidance in response to a request by a Green MP.
Leaf blowers should not be used unless they are "indispensable", the ministry said.
However, the ministry said it was not planning to ban the devices.
The guidance comes after studies suggested insect numbers were plummeting in Germany and across the world, prompting calls for better protection.
A study in 2017 suggested that flying insects had declined by more than 75% over almost 30 years at 60 protected areas in Germany.
Scientists said they were not sure what had caused the dramatic decline in Germany. But experts say that, in general, insect decline is being caused by intensive agriculture, pesticides and climate change.
In February, a scientific review of insect numbers suggested that 40% of species are undergoing "dramatic rates of decline" around the world.
An action plan to protect insects, estimated to cost €100m ($113m; £85m), was announced by the German government in September this year.
Under its plan, the German government has sought to strengthen environmental regulations and restrict the use of pesticides.
The controversial weed killer glyphosate, for example, will be banned in Germany by 2023.
The German environment ministry's guidance about leaf blowers is the latest move to protect insects.
Leaf blowers can be "fatal to insects in the foliage", the ministry said.
"There is a risk that small animals are absorbed or blown and thereby damaged," the ministry said in a statement.
Noise emissions, pollution and harm to soil biology must also be considered when using leaf blowers, Silvia Bender, a species protection expert for the ministry, told the Augsburger Allgemeine newspaper.
Experts say insects make up the majority of creatures that live on land, and provide key benefits to many other species, including humans.
Many other studies in recent years have shown that individual species of insects, such as bees, have suffered huge declines, particularly in developed economies.