Beekeepers are preparing for a “devastating” three to five years after the fast-spreading varroa mite was detected in Greater Geelong and the Surf Coast for the first time.

The parasite, just 1-2mm long, multiplies in honey bee larvae and attaches to adult honey bees, eventually killing them and weakening colonies. They can significantly reduce honey yields and impact flora biodiversity, and untreated infestations can lead to honey bee colony collapse.

An Agriculture Victoria spokesman said four registered beekeepers had reported varroa mite in their apiaries across the wider Geelong region. Last month, the mite was detected in the Surf Coast.

Marc Carroll, president of the Lorne and Surf Coast beekeepers group, said the news had caused significant anxiety for local beekeepers, with the mite already detected in Inverleigh, Bannockburn and Torquay.

Mr Carroll, who cares for about 60 beehives between Lorne and Anglesea, said beekeepers across the coast and Greater Geelong were bracing themselves for a “devastating” next three to five years as they learnt how to manage varroa mite in local hives.

“Varroa mite is very devastating,” he said. “You can treat your hives but within two weeks the mites are back. Beekeeping is about to become a lot more expensive and time-consuming.”

He said infestations were likely to become worse as mites multiplied in feral beehives or if hobby beekeepers didn’t know their hives were infected.

Earlier this year Victoria joined other Australian states, territories and industries in transitioning from eradication to management of varroa destructor.

Beekeepers now have access to Victorian bee biosecurity officers who can assist with developing the skills and knowledge to manage varroa and maintain healthy beehives.

The Agriculture Victoria spokesman said beekeepers across Victoria should regularly check their hives. “Early detection is important,” he said.