Maria Lupton has New Zealand's only leech farm, with tens of thousands of the parasites in tanks on her Waikato property.
If it's a nice fine spring weekend, then Maria and Robert Lupton know they'll probably get a call from a hospital asking for their leeches.
The Waikato couple owns a leech farm supplying hospitals throughout the country to help in surgery to restore blood flow to severed fingers or for restorative surgery after cancer treatments.
"Men and skill saws are very good for business," Maria says.
"It seems to be men more than women who are cutting fingers."
When an order comes in they will dispatch up to 300 leeches at a time.
"If I get a call from Christchurch at 2pm, they'll have them by 10pm."
They keep around 2000 leeches ready at a time from a stock of anywhere between 50,000 and 60,000 leeches.
And being ready means having leeches that haven't been fed fresh blood for anything between six and 18 months.
"The first warm weekend in spring often sees an upsurge in orders as do-it-yourselfers get out there and do-to-yourself.
"We sent leeches during the Covid shutdown. You might have recalled on TV all these people loading up their cars from Mitre 10 and Bunnings with timber and saws ... yes we got orders in shutdown."
The couple, originally from Northland, got into the breeding and selling of leeches by accident.
"It was not something we set out to do."
On a farm north of Dargaville, they and their children discovered the dune lakes were full of eels and leeches. At the same time, an Auckland Zoo scientist was doing a creepy-crawly exhibition and came to find leeches.
"Our kids were coming home with bucketfuls. Our daughter said 'we can get leeches' so long story short, we ended up sending leeches to the zoo.
"They were lining people up once a month to feed them. And that started a controversy; can you get AIDS or hepatitis from feeding leeches. (The answer is we don't know.)
"That put them in the paper. And a surgeon at Middlemore saw the article and they had a patient they had done a lot of work on but were in danger of losing what they had sewn back on. He rang the zoo and they referred him to us.
"Luckily it was springtime and the leeches were out of hibernation so the kids went down and got some, we put them in an ice cream bowl. It did the trick and away it went.
"The surgeons started asking for more. We thought we better start keeping them because they hibernate in the winter and the ponds go dry in a drought in Northland - the leeches disappear into the mud. So you can only reliably get them for two to three months in the spring."
So they started storing and breeding them.
They shifted farms to Waikato and started paying families to find leeches, but they soon started to worry about hygiene, the supply of quality leeches and other issues.
"Fencing off waterways from cattle is not beneficial to leeches because the best leeches feed off cattle when the animals stand in the water. We noticed that where waterways are fenced off the leeches become smaller and skinnier."
So they started to breed their own. At first, it was trial and error. There's no manual for breeding leeches, Maria says.
Their 60,000 leeches, all hermaphrodites with a life expectancy of around nine years, are now held in fish tanks in a renovated cowshed. And fed with blood from the nearby meatworks.
"They swim quite gracefully; a nice side-to-side motion," Maria says.
The leeches are used to solve a significant problem in plastic surgery. Surgeons can reattach a finger and join the arterial flows but often not the venous flow. That means blood pools and the area can become gangrenous.
"So they put leeches on every half an hour around the clock for three to five days.
"The leech injects a cocktail of drugs - local anaesthetic, flow enhancers, anti-coagulants. And it is that flow of blood which is now oxygenated which allows the body to heal and restore a return flow. The vein will regrow itself."
Her husband Robert has had his own experience of leeches after an accident.
Does it hurt?
"You only feel it for the first 20 to 30 seconds," Robert says. "Then the leech injects an anaesthetic and you don't feel it.
"It's a bit like a drip of cold water on hot skin; you feel them grinding for a bit and then it stops."
Maria says the use of leeches has become more mainstream and accepted in plastic surgery units around the world but it is also a part of traditional medicine in some parts of the Middle East, Russia and Turkey.
"In fact, in Russia, some ladies use them for wrinkle reduction."
In France, hospitals have been using leeches to prevent blood clots after surgery but have been looking into whether they could be used in treatments of rheumatism and osteoarthritis.
Now the couple take leeches with them when ever they go on holiday - just in case they get a sudden order.
"We'll take a couple of hundred leeches with us and a packing slip. The phone will ring and we will stop somewhere and pack them off, then get going.
"So yes we go on holidays with the leeches."