17th June 2026
After a period of wet weather preceded by a hot, dry spell across many parts of the UK, SCOPS (Sustainable Control of Parasites in Sheep) is urging sheep farmers to be extra vigilant when monitoring parasite burdens in lambs.
Nerys Wright, Technical Adviser for SCOPS, warns that the recent conditions could create a perfect storm for increased worm challenges on pasture.
“Wet weather creates ideal conditions for worm larvae to survive and move up the grass stem, increasing the risk of ingestion by grazing lambs,” says Nerys. “It can also release large numbers of larvae from dung pats as they break down, further increasing the challenge”.
While SCOPS encourages farmers to carry out regular faecal egg counts (FECs) to monitor parasite levels and make informed treatment decisions, they must also be on the guard when conditions lead to a sudden increase in infective larvae on pasture.
“It is really important to consider how lambs are performing in terms of daily liveweight gains (DLWG) and their general appearance because there can be a delay of two to three weeks between larvae being ingested and eggs appearing in the faeces, so farmers must trust their stockperson’s eye and daily liveweight gain alongside FEC results,” Nerys adds.
SCOPS is reminding farmers that proactive parasite control is not about routine blanket treatments, but about using tools like FECs, grazing management, DLWG to pick up worm challenges before FECs start to rise, and targeted treatments to manage or delay the development of wormer resistance and protect animal health.
“By testing regularly and acting early, farmers can avoid performance losses and reduce the need for whole-flock treatments,” says Nerys. “It’s about being strategic and responsive to the conditions on your farm.”
Nematodirus Update
Most of the UK is now in the post-hatch phase for nematodirus larvae, but sheep farmers in some areas should remain vigilant. Much of Scotland and parts of Northern Ireland are currently at peak hatch (shown by a black dot on the SCOPS Nematodirus Forecast map) or just after peak hatch (shown by a red triangle), meaning at-risk* lambs born in April and May could face a significant challenge.
In some hill and upland areas of England and Wales, a significant hatch may still occur, posing a threat to later-born lambs, particularly at higher altitudes or on north-facing grazing where hatching can be delayed beyond the model’s predictions.
*Any decision on if and when to treat for Nematodirus should be based on two factors: the lambs’ age and pasture contamination, and the temperature profile where they are grazing.
Lamb and pasture factors – are they at risk? Watch a short video here.
