It's not very often 600 new livestock arrive through the letterbox. But each week for the last month, Ruapuke Farmer Simon Thomson has been getting his new dung beetles in the post.
"It's a little bit weird because you know you're releasing these little fellas and there's very little to see of them once you put them in the soil," Thomson said.
The new arrivals swiftly settle into their new home, a "faecal environment" on Thomson's drystock Ruapuke farm.
"We're placing twenty bugs per cow pat.
"They're going to have a feed, have a bit of sexy time, burrow down, make some holes, lay their larvae in there.
"The bugs will come back up and they'll keep following the herd as they move on and in eight to 10 weeks these little fellas will come up from their burrows, sniff for where the closest manure is and fly off and dive into that."
The tiny critters are close to the bottom of the food chain, but they are part of a broader mission - to reduce effluent runoff and reduce methane emissions.
Along the way, they minimise the spread of parasites when the cow pats are buried into the ground.
"The burrows with this species are about 20cm deep, so that is integrating the manure down to that depth.
"It is bringing sub-soil up when they're digging so that mixing is good is for the soil profile, creating aeration and drainage channels which are good for your pasture growth, and also channels for the roots to grow down.
"The burrows are also useful for other soil biology to get plant matter and food and air and everything down in there - so it supports the whole biology."
Interest in dung beetles is growing with New Zealand's only supplier, Dung Beetle Innovations having to double its beetle colonies to meet more than 50 orders each week.
"Currently this season we have had far more orders than we have beetles," co-founder Shaun Forgie said.
"As a result of that we're expanding our facilities to be able to cope with the demand to do catchment level, or regional level, or even national level releases."
The Ministry for Primary Industries is showing some interest. It's invested $135,000 into a dung beetle test project which started in 2015 and ends this June. But Forgie thinks more needs to be done, and suggests the government needs to establish a nation-wide dung beetle scheme.
"It's such a big process that needs to be adopted on a large scale for it to take effect where you can actually measure it.
"It's great that farmers are doing it at a farm level but for it to actually take some sort of positive effect on water quality in a catchment, you need a catchment level or a regional level release of beetles.
"It's probably the only [solution] that addresses manure control at the source of the problem rather than once it's in the water."
Some regional councils support the use of dung beetles but Dairy NZ isn't convinced.
"The way dung beetles work does not significantly address the environmental issues dairy farmers face in terms of nitrogen leaching and greenhouse gas methane emissions," Dairy NZ spokesperson Bruce Thorrold said.
"Our research efforts are directed to initiatives which will make the biggest difference for dairy farmers and, for that reason, we have not invested in further research into dung beetles. We do not encourage the use of dung beetles, as there are more effective investments dairy farmers can make in environmental improvement."
But Thomson remains convinced of dung beetles' prowess to improve the farmer's bottom line by increasing grazing land.
"Animals will naturally avoid grazing around a cow pat, they don't want to eat next to their buddies poop. So the dung beetles come in, break up that cow pat, perforate it, it gets dried, rained on, UV light, so it gets sterilised.
"And by the time they come back onto that paddock, the dung should be pretty much gone rather than these cow pats sitting there for weeks and months.
"So effectively your farm is larger," he said.