A 260 per cent increase in the number of brown marmorated stink bugs found at New Zealand's borders has heightened a billion-dollar risk to the Bay of Plenty economy.

Ministry for Primary Industries figures provided to the Bay of Plenty Times show a total of 2569 individual bugs were found in September 2017 to April 2018. This period of time is known as the "risk season" when stink bugs from the Northern Hemisphere are most likely to crawl into cargo heading to New Zealand.

So far this season, biosecurity officers have detected two dead bugs, which were destroyed.

Kiwifruit Vine Health chief executive Stu Hutchings said the impact from the bugs could be massive for the local industry. In Italy the bugs have been found to cause up to a 40 per cent drop in kiwifruit prior to harvest by damaging the fruit around the stem when the bug feeds off the fruit and soften it around the top, he said.


"This could wipe income of growers and have an impact on GDP of between $1.8 billion by 2038," he said.

"The horticulture sectors' export value could fall by up to $4.2 billion."

The stink bugs are voracious eaters and during winter hibernate in people's houses. If disturbed, they give off a nasty smell like that of a skunk or old socks. After winter they then come out and eat everything as they search for a mate. They are also especially difficult to eradicate.

Hutchings said many plants, gardens, trees and native plants could be impacted by the bugs and many other industries could potentially be affected. The risk of an incursion was "constantly getting higher as we bring goods into New Zealand or people travel here".

Kiwifruit Vine Health was set up in December 2010 in the wake of the Psa outbreak. Since November 2012 it has been the lead organisation responsible for managing biosecurity readiness, response, and operations on behalf of the kiwifruit industry.

The organisation now joins a new Tauranga Moana Biosecurity Capital group which launched this week.

Of the 2569 stink bugs, most were found on cargo ships arriving at the Port of Auckland. Earlier this year four car carriers were turned away.

A ministry spokesman said risk vessels were all cleared at Auckland before heading to other ports such as Tauranga.


The reason why the stink bugs posed such a threat was they were hard to see, hard to kill, travel far and breed fast, he said.

Biosecurity New Zealand director border clearance services Steve Gilbert said it was increasing surveillance and inspection of arriving vessels and cargo from countries with established stink bug populations.

The stink bugs threat also prompted an amendment to rules, making it now compulsory for certain types of cargo to be treated before arrival, he said.