The weather has turned damp and mild after being dry and warm over the last couple of weeks and so, fly control is now needed.

The current weather conditions provide a perfect environment for flies to thrive and attack heifers and cows.

For your in-calf heifers or dry autumn calving cows, this can cause summer mastitis, which is an acute disease of the non-lactating mammary gland and is mainly caused by the bacterium Trueperella pyogenes.

The wet and mild weather looks set to continue for the next couple of days, so extra care, dosing, treatment and diligence may be required, particularly for autumn calving heifers and cows who will be beginning to spring up.

As cows and heifers begin to spring, their teat ends become a target for the flies to feed off and can lead to infection and damage of the quarter.

Summer mastitis often hits the same herds each year and quite often the source of the problem comes from certain fields.

The disease mainly occurs in the June to September period, affecting dry cows and in-calf heifers when fly numbers are highest, but can really occur at any time of the year and especially in mild and damp conditions.

The disease can severely damage the udder, cause high temperatures and toxaemia, and the infected quarters are generally lost. Treatment is focused on saving the animal and preventing pregnancy loss.

The quarter becomes hard and and swollen and when stripped, it will be foul-smelling and the cruds that come out may appear clear or soft to cheesy. As the infection progresses, blood may be drawn.

If the condition is not advanced, the infected quarter should be treated with intramammary tubes and the cow placed on a course of antibiotics.

In more severe cases, the cow or heifers should be placed on a course of anti-inflammatory drugs and in some cases, the vet will opt to amputate the teat to allow it to drain freely.

In all cases, the cows' affected quarter should be frequently stripped out to reduce toxin build-up and the cow isolated from the group.

Fly control in lactating animals and keeping up-to-date with pour-on intervals is crucial to prevent any reductions in milk production or feed intake, as well as the spread of diseases such as summer mastitis and pink eye.

Look out for signs in the parlour and the paddocks for irritation, as cows provoked by flies will be agitated, jumpy, and kicking a lot more in the parlour, while out in the paddock, you may notice tails swaying a lot more.

Using dry cow tubes for more susceptible heifers might be an option, but strict care and hygiene is needed so that dirt is not introduced to the teat canal or the teat end damaged.

Teat sealers will also minimise disease, as the teat seal plugs the teat, preventing bacterial transfer from the environment and flies.

They should be considered on heifers, even though you may need to organise a turn-over crate to get them done. This is something to potentially look at, especially for autumn calving heifers as they spring up in the high-risk time.

Using pour-on or other products to control flies near or around stock and to prevent summer mastitis is important. Apply these along the back of the animal and it may be no harm to direct some around the udder area as well.

These products should be used as instructed to ensure maximum effectiveness. It is generally advised to poured them on cattle every four to eight weeks. In the latter end of the summer when risk is high, consider a pour-on every four to five weeks.

Ear tags containing Cypermethrin are also available for fly control, such as Flectron tags, which come in boxes of 10. Once one tag is put into the cow's or heifer's ear, they are immediately effective and have a duration of up to four months.

Using Stockholm tar around the teats and udder at least once a week will help prevent flies, but in order to be effective, it has to be applied regularly. This method should only be considered if all other methods are not proving effective as this is more time-consuming.

Fields that are well-kept, with tight residuals and topping, reduce habitat where flies can thrive, therefore reducing the risk. Keeping dry stock moving is essential, allowing them to graze down tightly and providing them with fresh grass will impede this.

Also, it is important to avoid letting dry cows and in-calf heifers in fields that have a history of summer mastitis, typically where there is marshy ground, near a river, or has large quantity of trees and hedges.