Black Beetle Study

August 2011

Efforts to understand the prevalence of the pasture pest, black beetle

Black beetles have turned into a huge problem in the Waikato, Bay of Plenty and Northland regions, and a new research project focusing on the situation has just received half a million dollars in funding from MAF’s Sustainable Farming Fund. A new AgResearch tool called PestWebNZ is a way to find out more information about black beetles.

The Waikato Black Beetle Action Group, working with AgResearch, has just been awarded a three year MAF SFF grant for a project called “Beating Black Beetle: Developing Pest-Resistant Dairy Pastures in Waikato”. The grant is matched by a similar level of cash and in-kind contributions from DairyNZ, seed companies, industry and farmers.

Farmers from the Waikato and Bay of Plenty are experiencing widespread failure of perennial pastures, many within 12-24 months of successful establishment.

A recent survey of more than 700 Waikato and Bay of Plenty dairy farmers highlighted that pasture failure was the single biggest problem on-farm and black beetle was widely identified as one of the major culprits.

Despite the economic and environmental impacts of black beetle outbreaks, many farmers and rural professionals do not understand the extent of the problem or know how to combat it.

This project will inform Waikato farmers and the wider industry of the factors that result from damaging black beetle populations and how to minimise future pasture losses.

On-farm trials will find and show the best combination of currently available establishment/endophyte/cultivar combinations to limit future black beetle damage. Farms will be monitored for pasture production and composition, persistence through time, pest insect populations and endophyte infection rate. The Waikato Black Beetle Action Group is also hoping to link with companies that may have breakthrough technologies to deal with black beetle.

The team will work on a warning system to initiate pro-active farmer decision-making. Predictive models for black beetle outbreaks were developed in the 1980’s, and will be updated.

From the PestWebNZ press release :

A team of scientists and farm consultants, led by AgResearch’s Dr Katherine Tozer, have been working on PestWebNZ, for the past 12 months. The developers hope it will be a key industry resource.

The website currently covers 31 key New Zealand pasture weeds and insect pests, and will expand to cover more in the next year.

Sponsors for the website are the MAF Sustainable Farming Fund, Beef + Lamb NZ, DairyNZ and AbacusBio.

A key feature of PestWebNZ is a free alert service which sends emails to subscribers about outbreaks or potential outbreaks of insect pests, along with suggestions for their management.

Dr Tozer says PestWebNZ provides independent information to help farmers and consultants make pest management decisions, leading to better control and reduced productivity losses.

It provides information on identification, control, biology and impact of key pasture weeds and pests.

The site can be searched by weed or pest name or by what the species looks like. The site gives information on the biology of the pest or weed, an impact assessment and options for management and control.

The site does not reference commercially branded products, but instead gives users the chemical names that they can take to a retailer who can suggest an appropriate insecticide or herbicide.

Dr Tozer says, “It has been an enjoyable experience to collaborate with the many people involved, including experienced entomologists such as Colin Ferguson who have prepared all the pest information and are drivers behind the alert function.

The enthusiasm and input of Simon Glennie, a consultant from AbacusBio, has helped to ensure that the website is meeting farmers’ expectations. There has been strong industry and local council support, which is essential for the success of PestWebNZ.”

The website address is

Black beetles are tricky little guys and turning out to be very expensive for farmers in the northern parts of New Zealand.

AgResearch’s Warren King from Ruakura says they eat grass roots and like open free-draining soils, and even more than that they love peat soils with their high organic matter.

They came originally from South Africa more than 50 years ago, and in the last few decades there have been short-lived outbreaks every six to eight years or so.

But something has changed in terms of their ecology, and now there have been three seasons in a row with very high black beetle numbers through Waikato, Bay of Plenty and Northland.

They are hard to kill: frost doesn’t kill them; you can’t drown them. They can fly if they need to, and they can swim. They love hot weather, and a warm, wet autumn suits them down to the ground. They cause the most damage in summer, and they can kill pasture really quickly. They over-winter as adults.

A lot of farmers are now in serious trouble with their pastures because of black beetle, Warren says. “We have recorded numbers as high as 100 larvae in a square metre.”

Warren says across the upper North Island, where 40% of NZ’s milk production occurs, even a cost of 50c/kgMS is staggering. The cost to the industry is in tens of millions of dollars, he says.

He has three objectives for the new project:

1. Awareness raising amongst farmers, seed merchants and the rest of the industry

2. Testing and demonstrating three tools to help manage black beetle

3. Trying to understand the beetle’s ecology a bit better because the last research on it was about 30 years ago

He hopes to be able to say, for example, that the beetle’s increase might be related to climatic changes in years of La Nina.

The three tools for managing black beetle are:

1. Spend time out of grass to starve them. Beetles don’t eat clover. With heavy black beetle infestations, clover is often the only thing left. Plant maize or turnips or chicory in between grass. You might need to have two successive summers out of grass with a winter crop in between.

2. Use specific endophytes if planting perennial ryegrass. AR1 endophytes are highly favoured by black beetle, so inadvertently we have made the problem worse by using this endophyte. However AR37 is the pick of endophytes to give protection against the beetle and NEA2 is showing some promise. This process has to be managed well into the paddock.

3. Seed treatment to protect the seed for six to eight weeks in autumn when the beetles emerge as adults and are voraciously hungry

This is Martin Henton’s 33rd season as a dairy farmer. He milks 320 cows on 112ha.

He first noticed black beetles on the farm six years ago, and since then they have got worse each year.

“I talked to an ex-scientist who had done some work in the 1970’s, and he said it would disappear as fast as it arrived. But at my farm the population was building each year.”

“I got the guys from AgResearch and DairyNZ out to the farm a couple of years ago to look at the damage. They suggested applying for a research grant through the Sustainable Farming Fund.”

“I had planted a lot of new grass, the new tetraploid AR1, and the more I planted the more of a black beetle problem I was creating. Coupled with warmer temperatures, drier weather and light peaty soils, we have a population explosion.”

“In the 1940’s and 50’s when previous research was done, the southern limit of black beetle was Clevedon near Auckland. Now it has spread way further south to the Bay of Plenty, Taranaki and Tokoroa.”

“While flying my microlight I could see a lot more of the Waikato than the average farmer can. That is when I learnt to recognize the problem; the more I looked the more I found. It was over thousands of hectares.”

“I estimated it has cost me $1/kgMS/year to cope with it. This is the cost of bought-in feed, lost production by the cows, the cost of re-establishing pastures with undersowing, seeds, and diesel, time and effort.” He now has an in-shed feeding system, and is very unhappy about having to feed his cows like this.

He was very proud of his low-cost operation, but that has all gone.

“The only thing we have done is stop planting AR1 and switched to AR37, but black beetle will still eat AR37.”

“Endophytes only work above the ground, and the larvae are below the ground.”

Martin wants farmers to understand current best practice and how that will help limit the damage. “AR37 is one small tool that helps at the moment until we come up with something better.”

He says it is the worst problem he has had on the farm, definitely worse than drought. “When the drought breaks the grass grows. The only thing that grows after black beetle is weeds. The beetle has eaten all the grass.”

In the worst year so far he has lost nearly half the grass on the farm, and had to resow it. This year he has resown 25% of the farm.

He wants to know why there has been such a huge outbreak and how it can be predicted so farmers have some warning in advance.

Martin is relieved the funding has been approved because it has taken three attempts to be successful with funding. “It’s been a long journey, and it’s so frustrating that funding was declined for two consecutive years.”

He says the investment in the research will be richly rewarded compared with the cost the beetle is causing in damage on individual farms.

“I have lost $100,000 myself in one year; one farmer with 800 cows lost $300,000 in one year.”

For every 366 cows a Waikato farmer milks on peat or light country, they could lose on average $100,000 a year with damage,

Farmer Martin Henton has estimated the beetles have cost him a “staggering” $1/kgMS to pay for brought-in feed and pasture renovation. He now has an in-shed feeding system, and is very unhappy about having to feed his cows like this.

Farmers can use the new website PestWebNZ to find out information about both pests and weeds: and black beetle is one of the pests listed.

With a mystery weed or pest in their hand, a farmer can work through the questions and find out what the weed or pest is. Or they can go straight to the pest or weed and find out information about its life cycle, impacts, control and key characteristics.

There’s also an early warning system associated with it, where farmers can get an alert if population numbers of a particular pest are building up. This service is free to registered users.

Katherine says the service will keep being added to and refined, increasing from the 31 pests and weeds on there at the moment.

It’s also possible to record observations on the website.