Farmers and shearers report a significant increase in the incidence of blowfly strike in recent days. This is not surprising given the damp, humid conditions in recent days.

Reports are generally greatest in lambs that have not received any preventative treatment but there are also reports arising of dry hoggets and ewes that have a few weeks wool regrowth present along of course with ewes that still have to be shorn.

Table 1 details preventative and treatment options currently available on the market. It focuses on blowfly strike as the main concern but also provides information on other external parasites such as ticks, lice and sheep scab.

It is important to note that products differ significantly in the length of protection they offer, their withdrawal period and if they prevent and/or treat blowfly strike.

CLiK and CLiK Extra provide the longest period of protection for blowfly strike at up to 16 and 19 weeks respectively. They also have the longest withdrawal period and this should be taken into account where treating lambs that are approaching slaughter weight.

Youngs Vector is the only pour-on product that has preventative properties for both blowfly strike and ticks.

There are a number of spot-treatment products that provide protective cover for ticks, but these will only treat an established blowfly strike and provide no preventative cover in this regard.

Farmers carrying out plunge-dipping in Ireland have another option with the return of Cyperguard to the market. It is a non-organophosphate-based product and will treat and prevent blowfly strike, while it is also capable of treating and preventing tick infestations. It is not licensed for use in Northern Ireland and Britain.

Application procedure

The application procedure for plunge dips does not change depending on the parasite being targeted. The recommendation is to retain sheep in the solution for at least 60 seconds (head immersed fully once or twice), so that any scab present will be treated and resistance to scab mites will be avoided.

In terms of pour-ons, it is important to note that protection for products such as Ectofly and Youngs Vector will only be provided on the area of the fleece coming in contact with the product. It is therefore important to ensure accurate applications to the high-risk areas of the back, rump and tail-end.

Where animals have a dirty tail-end, dagging should occur before the product is applied. There is also a different type of nozzle required if applying product for blowfly strike and other parasites such as ticks/headflies.

Read the manufacturer’s guidelines carefully as recommendations can vary between products.