A rise in glue traps attached to trees to tackle invasive moths is killing bats, the head of the Mammal Society has said amid warnings of a "biodiversity emergency".
Tree barrier glue is used to protect fruit trees from caterpillars which would eat the whole crop.
However, environmental campaigners have argued that bats feed on these grubs, so it would be better for biodiversity and the orchards if the mammals were encouraged.
Fiona Mathews, who chairs the Mammal Society, said: "The trend for 'tree glue', marketed as environmentally-friendly way to kill moths and ants, is terrible.
"This stuff is horribly dangerous to bats that get stuck to it. If you want natural pest control, encourage bats."
The Royal Horticultural Society has said the use of the traps, which entangle moths, is sometimes required to protect fruit from insects. However, it argues that the glue used should ideally not be strong enough to capture larger animals such as birds or mice.
The charity advises: "Grease bands and tree barrier glues (horticultural grease) are mainly used to protect fruit trees, such as apple, plum, pear and cherry from winter moth caterpillars.
"These caterpillars can feed on developing fruit buds and so can reduce the amount of fruit produced. On ornamental trees, the damage can be tolerated as it will not affect the long-term health of the plant. The caterpillars are an important food source for nesting birds in the spring."
The BBC Springwatch presenter Chris Packham said he did not think these traps should ever be used, adding: "Why kill moths and ants? Why? It doesn't make sense. Who makes this c--- and why on Earth are they allowed to sell it?
"For God's sake wake up. There is a biodiversity emergency – we've lost almost 70 per cent of our wildlife since 1970. We don't need this nonsense now."
The Government is due to consult on a ban on glue traps used to kill "pest" wildlife because of the suffering they can cause, and ministers have said alternate, more humane methods exist to keep homes, gardens and businesses pest-free.