PEST GUIDE
How to identify and manage wireworm
Narrow holes and tunnels through potatoes and roots. Identify the cause, protect the listed crops and use proportionate control.
13 sections
Identification
Wireworms are hard, narrow, yellow-brown click-beetle larvae with three pairs of short legs near the head. They leave neat tunnels in roots and tubers. They are more likely where grass or pasture was recently cleared.
Hard golden brown click beetle larvae in soil.
The relevant stage and feeding site are: Hard golden brown click beetle larvae in soil. Similar symptoms can come from weather, nutrient stress or another pest. Confirm fresh feeding or the relevant life stage before removing plants or taking control measures.
UK seasonality and monitoring
Risk is often greatest in ground recently under grass or pasture.
During this period inspect Potatoes, carrots and other root crops, concentrating on the crop stage and plant parts described above. Note when and where fresh injury appears; old feeding marks can remain after the pest has moved on.
Crops and plants affected
The recorded hosts are Potatoes, carrots and other root crops. This list identifies plants worth checking; it does not mean every crop is equally vulnerable. Start with the listed plants and inspect the tissue where this pest feeds.
Check affected crops for these signs: Narrow holes and tunnels through potatoes and roots. Match the symptom to a live pest, larva, egg or characteristic feeding sign before deciding that treatment is needed.
Damage and likely consequences
Narrow holes and tunnels through potatoes and roots. A small amount of old damage on a vigorous plant may be cosmetic. Continued feeding on roots, seedlings, growing points or edible parts can reduce establishment or yield.
On Potatoes, carrots and other root crops, judge severity by checking whether injury is fresh and spreading, whether the plant is still growing, and whether the edible part is affected. Avoid removing a crop based on one ambiguous mark.
Prevention
Use bed history to guide planting, especially where turf has recently been removed. Inspect suspect tubers for narrow tunnels.
Control and integrated management
Hand-pick larvae found while cultivating and avoid moving suspect soil into clean beds.
Natural predators and wildlife-conscious choices
Use rotation and cultivation rather than routine pesticide use.
For wireworm on Potatoes, carrots and other root crops, use a barrier or hand removal only where it fits the crop and life stage. Keep any cover taut, inspect it for trapped wildlife, and remove it when protection is no longer needed.
Long-term management
Rotate crops and do not plant the most vulnerable crops immediately after converting grass to a vegetable bed.
For wireworm on Potatoes, carrots and other root crops, record the bed, crop stage and date when fresh damage first appears. Those notes help time protection and monitoring before the same crop stage is vulnerable next season.
Common mistakes
A symptom alone is not a diagnosis. Wireworms are hard, narrow, yellow-brown click-beetle larvae with three pairs of short legs near the head. They leave neat tunnels in roots and tubers. They are more likely where grass or pasture was recently cleared. Look for a matching live pest or fresh feeding sign before intervening.
Finding a wireworm does not make the whole plot unusable; risk depends on bed history and crop.
If damage continues
Recheck Potatoes, carrots and other root crops where new injury is appearing, including the hidden feeding site: roots, folded leaves, leaf undersides, flowers or fruit as appropriate. If identification remains uncertain, photograph a live specimen alongside the damage and ask an allotment association or horticultural adviser.
If the recommended control (Lift promptly, remove damaged roots and avoid planting susceptible crops in badly affected ground.) has not helped, confirm that it was fitted or applied at the right crop stage and that fresh damage is still occurring. Old marks do not heal when the pest has gone.
Frequently asked questions
Does finding wireworm mean potatoes cannot be grown there?
Wireworms are hard, narrow, yellow-brown click-beetle larvae with three pairs of short legs near the head. They leave neat tunnels in roots and tubers. They are more likely where grass or pasture was recently cleared. Check Potatoes, carrots and other root crops, especially at the feeding site described above. Lift promptly, remove damaged roots and avoid planting susceptible crops in badly affected ground.
When should I start checking for wireworm?
Risk is often greatest in ground recently under grass or pasture.
How can I tell whether wireworm is still active?
Look for fresh damage and the relevant life stage. Narrow holes and tunnels through potatoes and roots. Old marks may remain after the pest has moved on.
What wildlife-conscious approach works for wireworm?
Use rotation and cultivation rather than routine pesticide use. Check covers and traps frequently, and remove them when the vulnerable crop stage has passed.