"It took me the rest of the day to walk home and my gumboot was full of blood," she says, displaying the scars.
"Then one day I got a rifle and it made it much easier. It is a .22 and I just shoot them. We had to kill the pigs or we wouldn't have had any lambs.
" They rip the newborn lambs open and just eat the liver. Most of the pigs I just roll into a gully, but I take the odd one home to eat. The most I got in one day was 23, and in a year was 501. Most years it was about 250 pigs."
Merle became a bit of a legend in the district after turning up at a local pig-hunting contest with 26 pigs on a trailer.
And she has more scars. She was out hunting when her dogs got on to a young wild bull.
The wild cattle in the backblocks of Taranaki have been there for about 100 years, left when early settlers walked off the land because it was too tough to farm. They are true wild beasts and can be dangerous to hunt.
A wounded bull becomes the hunter and this one had been shot before by a .22 and was not fond of people.
"The dogs rarked it up and I had to climb a tree. You always look for the nearest tree. I climbed a manuka but the branch broke and I fell right in front of the bull, which tossed me over its shoulder.
"Its horn ripped open my thigh and my dogs distracted it until a friend shot the bull, but I couldn't make it home. They had to get a helicopter in and I spent a few days in hospital."
That little adventure took more than 30 stitches to sort out. Another time, an angry bull attacked Merle and she spent three hours sitting up a tree until the animal lost interest and wandered off.
With 4450ha to look after, Merle worked the property on horseback in the years before quad bikes arrived, and she supplemented the farm's income by trapping possums.
She would live in small huts in the bush, cutting firewood to stay warm in the harsh winters and working her trap lines.
It is tough country and most of the families living in the valley have long gone.
"They were all mortgagee sales. The bank came visiting one day as they wanted to sell the farm because the mortgage was overdue.
"My father wasn't having a bar of it. He was waiting with the shotgun and told them if they came any closer he would shoot them.
"They took off and he eventually paid it off."
Now, most of the property has gone, cut into blocks and sold off, but Merle still goes possuming "for something to do". Possum trappers all have their favourite baits to attract the animals. It may be a drop of aniseed oil sprinkled on flour, or jam, or flour mixed with cinnamon.
Merle has a secret recipe which she refuses to discuss. "Possums will run about one night in 10 but you never know when, so you have to be out there."
Merle doesn't have a phone; she has outlasted two husbands, and the occasional neighbour or pig hunter in this remote area will drop in to see her, but one day she will probably head into the bush on her bike and never return.
