Farmers are constantly trying to control little pests around the farm that range from stomach worms in livestock to aphids in crops, rodents, rabbits and hungry birds.

The battle against parasites like stomach worms and liver fluke has become more difficult in recent years as they develop resistance to the various drugs used to control them. Scientists are now developing ways of making livestock immune to internal parasites.

Arable farmers are also finding it increasingly difficult to control crop pests as various chemicals, such as neonicotinoids that were used as a seed dressing to protect crops like oilseed rape from cabbage stem flea beetle, are withdrawn from the market. Neonicotinoids were banned by the EU because they were implicated in the decline of bee populations.

It's much the same with rodents like rats where anyone purchasing rodenticides now has to undergo training to show proof of competence. That legislation was introduced as a result of concerns by wildlife groups that their improper use was putting wildlife, including listed species, at risk.

Studies showed that rat poison is toxic to non-target species including stoats, barn owls, red kites and kestrels that inadvertently ingest those chemicals when eating poisoned rodents.

I have regularly written about the never-ending war arable farmers are fighting with flocks of ravenous birds like wood pigeons and crows intent on devouring their crops - but there are other birds like starlings that can also eat into a farmer's profits. Flocks of starlings feeding on fragments of cereals and protein in rations provided for cattle indoors can eat as much as £1 worth per cow per day. That means that a dairy farm with a large herd could be losing thousands of pounds annually if the pests aren't controlled.

Keeping those feathered thieves out of cattle sheds by means of erecting nets can cost thousands of pounds. That could be about to change as it has been discovered that starlings can be deterred by adding a garlic-based feed extract to rations.

Research by Bridgewater College Farm in Somerset found that incorporating a small amount of the garlic-based additive in feed rations discouraged starlings from entering farm buildings to feed. While cattle were unaffected, the polysulphides in the product cause stomach irritation to the birds, and after a week to ten days they associate the smell of the product with the irritation and avoid it.

Birds like are also vectors of animal diseases, while generations of fruit growers have had to cover their ripening crops with nets.

Elsewhere on the farm rabbit populations have to be contained by shooting, gassing, snaring and trapping, while newly-planted hedges need to be protected by expensive rabbit-proof netting that is set into the ground to prevent the bunnies from burrowing underneath.

This is the time of year when farmers start to trap moles. They may seem harmless creatures that spend all their time underground and out of sight that, unlike rats and mice, never nibble expensive grain or animal feed. Unfortunately, the hillocks left behind as a result of their tunnelling contain small stones that cause expensive breakdowns with mowers and silage-making equipment.

Worse, soil from those mole hills contaminates the silage and leads to a fatal disease in sheep called listeriosis.

At one time we sprinkled strychnine, a deadly poison, over worms we gathered from behind a plough, and placed them in mole runs where they were found and eaten. Strychnine was withdrawn from use in 2006 under an EU directive on human and environmental protection standards.

In the absence of strychnine, some farmers have resorted to using tablets containing aluminium phosphide that give off a deadly gas when placed in mole runs - but, as was the case with strychnine, you need to be properly trained in their use to be allowed to purchase them.

Many farmers have gone back to the laborious method of setting traps in the main tunnels, or runs as we call them. Main runs are usually located close to drystane dykes, under the bottom wire of a fence, or just above a sheep track on steep ground.

Moles aren't daft and tunnel their main runs where they are unlikely to be trampled by the hooves of grazing cattle or sheep. Another favourite run to trap is the one that heads to water, because moles have to drink regularly.

Setting and checking traps is time consuming, but as with other farm pests, moles have to be controlled.