Avocado and blueberry growers in northern New South Wales are on alert after a new varroa mite infestation was detected in local hives.

The varroa mite is considered a deadly pest for bees worldwide and growers are becoming increasingly concerned after the initial infestation in Newcastle Harbor spread north last month.

The NSW Department of Primary Industries confirmed on Tuesday that another infestation had been detected near Nana Glen, north-west of Coffs Harbour.

The current map of the emergency zone for the Varroa mite in NSW.

There are now 43 infested locations across the state.

“NSW DPI has established emergency zones around infested facilities and has implemented significant measures to stop the spread of the varroa mite,” a DPI spokesperson said.

NSW Farmers Coffs Harbor local branch president Paul Shoker said the new outbreak had growers concerned as pollination season approached.

"Without bees, we can't grow avocados or blueberries or many other crops," Shoker said.

“Community reporting is a vital part of control measures and people should continue to report hive locations, both managed hives and wild hives, that they may be aware of.”

The Northern Rivers region, which includes Coffs Harbor to the Queensland border, produces a substantial amount of Australia's blueberries and avocados.

Varroa mites can only reproduce on bees and can quickly destroy any hive they infect.

A close-up of the varroa mite, which can infect bees and hives.

The parasite was first detected during routine surveillance at the Port of Newcastle on June 22.

Since then, DPI has established emergency zones around infested facilities to stop the spread of the mite.

"All beekeepers responsible for bee colonies or hives within the 50 km biosecurity zones are in the notification, eradication or surveillance zones," said the DPI spokesman.

“In those areas, beekeepers must tell NSW DPI where their bees and hives are.

"This includes caged queen bees and packed bees."