Buckets of sand, the right climate and a snack of carrots on the side help one of the country's rarest and most elusive critters get in a romantic mood.
The scene is set at AgResearch Invermay, where a breeding programme is under way with the aim of boosting the population of endangered Cromwell chafer beetles.
An 81ha reserve near Cromwell dedicated to the chunky flightless beetles is the only place in the world the insect is found.
Because they are flightless and unable to move far, the beetles are vulnerable to loss of habitat.
"Their uniqueness makes them very important to us and, in fact, this was the first reserve in the country to be set aside for an insect," AgResearch scientist Barbara Barratt said this week.
The breeding programme is a joint venture with the Department of Conservation, and the road to romance starts with a night-time walk.
"In early spring, there's a team of people who come out at night to the reserve with torches and lanterns to catch the adult beetles. It's a bit hit and miss and they [the beetles] don't always come out but if you see them, they're easy to catch. Then we send them down to Barbara and her team at Invermay," Doc biodiversity ranger Craig Wilson, of Alexandra, said.
About 50 males and 100 females - "it's easy to tell the sex once you know how" - are sent on a match-making mission.
Sand dunes are home for the beetles back in Cromwell so buckets of sand from the reserve provide a home away from home in the Invermay laboratory, complete with a range of tasty plants from the reserve and some carrots.
"During the day, the adults hide in the upper levels of sand and come out at night to feed. They like the roots of plants and we've discovered they're partial to carrots as well," Dr Barratt said.
The beetles seem happy to let nature take its course in the lab, and after mating, the females lay an average of 20-30 eggs in the sand.
"It's all in a temperature-controlled chamber and they don't like it too humid or too dry; it has to be just the right conditions, " she said.
The beetles are not too fussy about their partner.
With the adult's life span being only four or five months, once spring arrives, they get on with the business of reproducing.
"I wouldn't say they mate for life or anything. But we are still learning about them as we go along; there's a lot we don't know yet," she said.
The survival rate from the hatched eggs is high, about 70-80%, and the programme was initially aimed at raising them to adult level, but it has been difficult to get the larvae to pupate.
"That's something we're still working on - whether it's the diet or conditions that get them to pupate, " Dr Barratt said.
The goal is to breed a captive population so the species will survive if the numbers at the reserve decline for any reason.
Although the reserve is 81ha, beetles are found in only 10ha of that area.
Mr Wilson said a rough estimate put the population at between 60,000 and 70,000.
"But that varies from year to year and because it's such a small area, it's very much at risk."
Little owls, hedgehogs, rats, mice and redback spiders are among the predators who find the chafer beetles tasty.
The larvae, which take a year or more to reach maturity, are safer because they live further underground.
Rare insect
• Cromwell chafer beetles are among the rarest insects in the country.
• They are listed as nationally endangered.
• They are found only within an 81ha reserve near Cromwell.
• Reserve set up in the 1970s, first insect reserve in New Zealand.
• The beetles are flightless and nocturnal and live in inland sand dunes.
• Breeding programme started in case population dips.
• Predators include little owls and redback spiders.
