The saying ‘no two years are the same’ looks set to ring true for blowfly strike. Inclement weather and low temperatures in 2024 led to a low risk of blowfly strike until well in to the normal risk period. The opposite is the case in 2025, with a number of reports of blowfly strike over the last week to 10 days.
The strikes are not very aggressive as it is still early in the season, but they serve as a warning of a heightened risk. There is no change to the range of products available to farmers to treat and prevent external parasites. The only change in recent years has been on/off supply challenges.
The table below details external parasite control options, with blowfly strike taken as the focal point.
Notable information on other parasites targeted by the product are listed in the column on the right. For easier understanding the table has been split in to products licensed for plunge dipping and pour-on products.
The list is not exhaustive, but covers the main options available to farmers in Ireland and Northern Ireland. There are numerous other products licensed in the UK, but similar to Ireland the most common pour-on product used is the range of CLiK products.
The data for the products on the Irish market has been extracted from the Summary of Product Characteristics (SPC) published by the Health Products Regulatory Authority (HPRA) and, where applicable for UK-only products, from the Veterinary Medicines Directorate (VMD) Product Information Database. It is important that farmers are cognisant of any differences between product characteristics across different veterinary jurisdictions.
All sheep spend at least 60 seconds in the dipping tank and are fully immersed at least once.
Main considerations
It is clear to see that products differ significantly in terms of the range of external parasites covered, the length of protection claimed and whether or not products treat an active strike. The latter is an important point to remember where applying product to guard against blowfly strike and there is the possibility of active strikes being present. The other factor, which increases in importance as lambs get older, is the withdrawal period.
Plunge dipping products offer the most extensive level of cover against external parasites. The product listings have a claim period typically ranging from five to eight weeks. The length of protection can vary depending on a number of factors, including weather, the efficacy of dip in the tub and the correct dipping practices being adopted.
This is no different with pour-ons. Cyperguard is the only product in Ireland with a claim to treat ticks, although the ingredients in the Gold Fleece products are similar, with the UK product possessing a tick treatment claim.
Sheep remain in the dipping tub for at least 60 seconds with their head immersed at least once to cover sheep scab.
Pour-ons
Pour-ons have become the most common form of blowfly prevention earlier in the season. There are big difference in the level of protection offered, with CLiK products providing the longest duration of protection, but these also possess the longest withdrawal period.
An earlier application can often be a better fit in providing cover earlier in the season, while the application rate will also be lower with lighter lambs. There is no one rule which fits all circumstances and as such it is important to weigh up what works best for your farm.
The product of choice for many hill sheep producers in Ireland where ticks are an ongoing challenge is Young’s Vector, due to the fact that it provides protection against ticks, blowfly strike and headflies. Vectocert is essentially the same product and is available to farmers in the UK. It is worth noting that it’s SPC advises that for tick control for lambs less than 10kg to apply a 5ml treatment followed by 10ml three weeks later.
Dysect / Zermasect, which are also only available to farmers in the UK, have a different active ingredient to Young’s Vector and Vectocert, but also offer similar cover and two weeks’ longer blowfly protection. The big difference, however, is a 49-day withdrawal period. Ectofly is also similar to the above-named products, but its claim for tick control extends just to treatment and not preventative control. It is a common product in Ireland for shorter-term blowfly protection due to its short withdrawal date.
Crutching / dagging sheep will also reduce the risk of blowfly strike.
Top tips to maximise cover
The mode of action in products such as CLiK is insect growth regulators (IGRs) which essentially stifle any development. The UK body SCOPS explains that such products allow the female blowfly to lay her eggs, but then prevent the larvae developing, stopping the lifecycle. They prevent strike for eight to 16 weeks, depending on product choice. Important to note that they do not treat an existing strike.
Products with an active ingredient of cypermethrin/alphamethrin are pyrethroids work by disrupting an insect’s nervous system, ultimately leading to death.
The length of protection achieved can be strongly influenced by the method of application, the condition of the fleece and the temperature/sunlight. The following tips can help to maximise cover:
Apply product to a clean, dry fleece and time the application to avoid contact with rain for six to 12 hours post-application. Refrain from applying products during periods of intense heat where there is a risk of product evaporating before binding with the fleece. If product is being applied do so indoors or late in the evening. Many products provide protection where product comes in to contact with the fleece. As such, abide by manufacturers’ guidelines and cover high-risk areas, such as the shoulder, back and rump regions. Dag dirty tail ends before applying to extend the period of cover. Take note that some products have different applicators for blowfly, ticks, headflies.Read manufacturers’ guidelines or seek advice when purchasing. Organic farming
The number of sheep farmers participating in the Organic Farming Scheme in Ireland continues on an upward trend with over 3,000 sheep farmers and in excess of 200,000 ewes now farmed organically or in transition. The objective for external parasite control in the scheme is to control blowfly strike by mechanical means including shearing and regular crutching, dagging, etc.
However, chemical control options are permitted, if recommended and approved by your veterinary practitioner, for the prevention and treatment of blowfly strike and other external parasites. With regard to dipping, the use of organophosphate-based dips are not permitted with the non-organophosphate based dip, Cyperguard, the only plunge dipping product permitted.
Scheme considerations
There has been a greater focus on external parasite control in the last two years as it now features as actions in schemes. Flystrike control is an annual action in the Sheep Improvement Scheme (SIS) for lowland flocks which has been selected by a small number of participants.
Plunge dipping to control external parasites has been a more common option selected by participants in the National Sheep Welfare Scheme. Plunge dipping can be carried out on farm where facilities are available or by a mobile plunge dipping service operator. Documentary evidence of completion of this action will include, but is not being limited to, completion of the scheme action record sheets, receipts from a contractor and/or receipts for the purchase of appropriate dipping material.
The action must be carried out on the number of breeding ewes selected by the farmer as a payable number at application stage. The deadline is 17 October 2025 or 28 November 2025 where farmers have opted for the later completion date.
The saying ‘no two years are the same’ looks set to ring true for blowfly strike. Inclement weather and low temperatures in 2024 led to a low risk of blowfly strike until well in to the normal risk period. The opposite is the case in 2025, with a number of reports of blowfly strike over the last week to 10 days.
The strikes are not very aggressive as it is still early in the season, but they serve as a warning of a heightened risk. There is no change to the range of products available to farmers to treat and prevent external parasites. The only change in recent years has been on/off supply challenges.
The table below details external parasite control options, with blowfly strike taken as the focal point.
Notable information on other parasites targeted by the product are listed in the column on the right. For easier understanding the table has been split in to products licensed for plunge dipping and pour-on products.
The list is not exhaustive, but covers the main options available to farmers in Ireland and Northern Ireland. There are numerous other products licensed in the UK, but similar to Ireland the most common pour-on product used is the range of CLiK products.
The data for the products on the Irish market has been extracted from the Summary of Product Characteristics (SPC) published by the Health Products Regulatory Authority (HPRA) and, where applicable for UK-only products, from the Veterinary Medicines Directorate (VMD) Product Information Database. It is important that farmers are cognisant of any differences between product characteristics across different veterinary jurisdictions.
All sheep spend at least 60 seconds in the dipping tank and are fully immersed at least once.
Main considerations
It is clear to see that products differ significantly in terms of the range of external parasites covered, the length of protection claimed and whether or not products treat an active strike. The latter is an important point to remember where applying product to guard against blowfly strike and there is the possibility of active strikes being present. The other factor, which increases in importance as lambs get older, is the withdrawal period.
Plunge dipping products offer the most extensive level of cover against external parasites. The product listings have a claim period typically ranging from five to eight weeks. The length of protection can vary depending on a number of factors, including weather, the efficacy of dip in the tub and the correct dipping practices being adopted.
This is no different with pour-ons. Cyperguard is the only product in Ireland with a claim to treat ticks, although the ingredients in the Gold Fleece products are similar, with the UK product possessing a tick treatment claim.
Sheep remain in the dipping tub for at least 60 seconds with their head immersed at least once to cover sheep scab.
Pour-ons
Pour-ons have become the most common form of blowfly prevention earlier in the season. There are big difference in the level of protection offered, with CLiK products providing the longest duration of protection, but these also possess the longest withdrawal period.
An earlier application can often be a better fit in providing cover earlier in the season, while the application rate will also be lower with lighter lambs. There is no one rule which fits all circumstances and as such it is important to weigh up what works best for your farm.
The product of choice for many hill sheep producers in Ireland where ticks are an ongoing challenge is Young’s Vector, due to the fact that it provides protection against ticks, blowfly strike and headflies. Vectocert is essentially the same product and is available to farmers in the UK. It is worth noting that it’s SPC advises that for tick control for lambs less than 10kg to apply a 5ml treatment followed by 10ml three weeks later.
Dysect / Zermasect, which are also only available to farmers in the UK, have a different active ingredient to Young’s Vector and Vectocert, but also offer similar cover and two weeks’ longer blowfly protection. The big difference, however, is a 49-day withdrawal period. Ectofly is also similar to the above-named products, but its claim for tick control extends just to treatment and not preventative control. It is a common product in Ireland for shorter-term blowfly protection due to its short withdrawal date.
Crutching / dagging sheep will also reduce the risk of blowfly strike.
Top tips to maximise cover
The mode of action in products such as CLiK is insect growth regulators (IGRs) which essentially stifle any development. The UK body SCOPS explains that such products allow the female blowfly to lay her eggs, but then prevent the larvae developing, stopping the lifecycle. They prevent strike for eight to 16 weeks, depending on product choice. Important to note that they do not treat an existing strike.
Products with an active ingredient of cypermethrin/alphamethrin are pyrethroids work by disrupting an insect’s nervous system, ultimately leading to death.
The length of protection achieved can be strongly influenced by the method of application, the condition of the fleece and the temperature/sunlight. The following tips can help to maximise cover:
Apply product to a clean, dry fleece and time the application to avoid contact with rain for six to 12 hours post-application. Refrain from applying products during periods of intense heat where there is a risk of product evaporating before binding with the fleece. If product is being applied do so indoors or late in the evening. Many products provide protection where product comes in to contact with the fleece. As such, abide by manufacturers’ guidelines and cover high-risk areas, such as the shoulder, back and rump regions. Dag dirty tail ends before applying to extend the period of cover. Take note that some products have different applicators for blowfly, ticks, headflies.Read manufacturers’ guidelines or seek advice when purchasing. Organic farming
The number of sheep farmers participating in the Organic Farming Scheme in Ireland continues on an upward trend with over 3,000 sheep farmers and in excess of 200,000 ewes now farmed organically or in transition. The objective for external parasite control in the scheme is to control blowfly strike by mechanical means including shearing and regular crutching, dagging, etc.
However, chemical control options are permitted, if recommended and approved by your veterinary practitioner, for the prevention and treatment of blowfly strike and other external parasites. With regard to dipping, the use of organophosphate-based dips are not permitted with the non-organophosphate based dip, Cyperguard, the only plunge dipping product permitted.
Scheme considerations
There has been a greater focus on external parasite control in the last two years as it now features as actions in schemes. Flystrike control is an annual action in the Sheep Improvement Scheme (SIS) for lowland flocks which has been selected by a small number of participants.
Plunge dipping to control external parasites has been a more common option selected by participants in the National Sheep Welfare Scheme. Plunge dipping can be carried out on farm where facilities are available or by a mobile plunge dipping service operator. Documentary evidence of completion of this action will include, but is not being limited to, completion of the scheme action record sheets, receipts from a contractor and/or receipts for the purchase of appropriate dipping material.
The action must be carried out on the number of breeding ewes selected by the farmer as a payable number at application stage. The deadline is 17 October 2025 or 28 November 2025 where farmers have opted for the later completion date.
SHARING OPTIONS