Arson squad detectives are investigating the fires, many of which are understood to be linked.
The fire spree began close to the Mundaring town centre on New Year’s Day. A small fire on Mundaring Weir Road, near Jacoby Street, was quickly contained.
A second fire is believed to have been deliberately lit on a bush track off Moola Road, Glen Forrest, on February 9.
Another suspicious blaze followed in Chidlow nine days later.
They were followed by two more fires described by investigators as ‘suspicious’ ” on Orchard Road, Wooroloo, on February 24 and on Hardey Road, Glen Forrest, the following day.
Police have joined with the Shire of Mundaring in calling for community assistance to help stop the attacks.
Sergeant John Browne, of Mundaring Police, asked for public help in locating those responsible for lighting the fires.
‘People can help us by writing down as much information as possible and reporting any suspicious persons or vehicles,’ Sgt Browne said.
‘Every piece of information you provide is important.
‘Your assistance could help police prevent a bushfire occurring or could lead to an arsonist being apprehended.’
Shire President Helen Dullard said residents could assist police to stop arson by being the community’s ‘eyes and ears’.
‘As a community, we need to stand together and say this type of behaviour won’t be tolerated,’ she said.
‘We all need to play a part in stopping arson, which puts lives and properties at risk.’
Meanwhile, police are searching for a possible arsonist following a number of deliberately lit scrub fires near Brigadoon early on Thursday.
The Department of Fire and Emergency Services was called in to bring the fires under control.
The first was reported in bushland at Rollinghills Drive just before midnight. Fires on Cathedral Avenue and in the Bell’s Rapid area were later reported in the same area.
DFES and police said investigations were continuing.