Pest controllers warned people to be on the lookout for the Brown-tail moth (Euproctis chrysorrhoea), which can cause breathing problems, especially in asthma sufferers.
Cleankill Pest Control was called after the moths were seen in offices in Portsmouth, echoing similar incidents in Croydon and Exeter. A pesticide barrier was used to stop the bugs crawling into the buildings or colonising other hedges and trees for the emerging moths to devour leaves.
Cleankill managing director Paul Bates said: "We are getting more calls this year. We believe the unusually warm spring has contributed to the moths spreading. As well as a health hazard, they will strip a tree of foliage."
The caterpillar of the brown-tail moth is brown, has a dotted white line down each side and two distinctive red dots on the back of its tail
It is a voracious eater of vegetation, especially in spring, and although it prefers hawthorn and blackberry, it will eat practically any type of tree or bush.
For more information see John Adlam's Brown-Tail moth Pest and Disease Factsheet.