Leatherjacket menace more widespread

FARMERS, groundsmen and park keepers across Scotland have been warned leatherjacket densities are at their highest recorded levels in 39 years.

The annual survey carried out in west and central Scotland by experts from Scotland’s Rural College (SRUC) indicates the number of the insect pests puts farmland, golf courses and other large areas of grass at extreme risk of damage.

Leatherjacket is the name given to the grubs of the crane fly or “daddylong-legs”.

They live just below soil level and, from August through to the following June, eat the roots of grasses and other plants.

Professor D av y McCracken, the SRUC ecologist leading the survey, said: “While over 90% of the fields sampled contained more than 0.6m grubs per hectare nearly 60% of the fields harboured populations of over two million per hectare.

“Densities like that, if left untreated, are likely to result in severe and visible damage to the grass sward or any spring crops sown after the grass.

“One result showed 13.6m grubs per hectare, the highest density we’ve ever found in one field.”

S RUC ha s been conducting the survey since the mid 1970s and these latest results show the value of long-term surveillance.

Leatherjackets are an important food source for some farmland birds which probe the soils in search of them.

However because of the damage the grubs do to grassland and crops the SRUC research has focused on what drives variations in leatherjacket populations.

In the past 14 years populations have been consistently higher, believed to be linked to climate change.

Professor McCracken continued: “Farmers have been calling in my SAC Consulting colleagues to check the damage being done, but this year we are also getting requests from urban businesses with large areas of grassland.

“It is also true to say that the problem applies far more widely across the country than previously.”

SRUC’s SAC Consulting division recommends that pre-ploughing insecticide treatments when the field is still under grass are more effective than those applied once any damage is under way in the spring-sown crop.

SAC Consulting offers a field infestation assessment service.