Colorado Beetle
Leptinotarsa decemlineata
Causative agent
The Potato beetle is a small beetle of 10 to 12 mm, reddish-yellow with several black spots on the thorax and five black bands on the elytrons (fore wings).
The adult lays yellow-coloured eggs in a cluster on the lower side of the leaves.
The slightly curved larva, yellow to orange in colour, has a double row of black spots on the abdomen.
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Description of symptoms on crops
The adults spend the winter in the soil (20 to 30 cm) and come up at the end of spring to feed on the first potato sprouts and sometimes even the skin on the stems. They subsequently do a great deal of damage due to their enormous appetite and the fact that they can consume all the foliage.
The larvae start to devour the leaves which are carrying them, then the neighbouring leaves almost up to the top of the plant. They rapidly consume a very large amount of foliage.
In the case of severe infestation, the defoliated plant can no longer provide growth for the tubers: the reduction in yield can be very substantial.
Control
- Avoid tillage while the larvae are trying to penetrate the soil (summer), since this facilitates their burial.
- Generalised chemical treatment. The larvae are easily killed by most insecticides, but the adults are very resistant.
A large number of insecticides approved for aphids are also effective against the potato beetle.
