New Colorado Beetle Colonies Found

27.7.2012

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Six Colorado beetle colonies have been found so far in Finland. Finnish Food Safety Authority Evira emphasizes the crucial importantance of commercial potato farmers as well as home farmers to independently monitor their fields for beetles.

New isolated Colorado beetle infestations have been found in Savitaipale (Etelä-Karjala), Kotka (Kymenlaakso) and Salo (Varsinais-Suomi). Earlier this summer infestations have been detected in Kangasniemi (Etelä-Savo) as well as Pornainen and Vihti (Uusimaa).

The infestations in Uusimaa are in the same locations as last year, but the rest are new findings of last summer’s beetles that have managed to overwinter in the ground.

In addition to adult Colorado beetles, one can now find larvae of different instars as well as egg clusters on potato plants. One can now find also pupae in the ground. At first, adult beetles and larvae eat up holes in potato leaves. The worst danger comes from the larvae which, in large populations, eat up nearly all the foliage. The plants destroyed by larvae colonies are easy to distinguish from the other plants.

There has been an exceptional amount of ladybirds in nature this summer, also in potato fields. The pupae of ladybirds bear some resemblance to those of Colorado beetles, but they are attached to potato leaves and do not move at all. Evira’s website includes photos of the ladybird at different stages of development, in order to make it easier to tell the species apart.

An adult beetle is about one centrimetre long and has ten black longitudinal stripes on its yellow back. Its yellow-orange eggs, about the size of a semolina grain, appear in compact masses on the underside of potato leaves.

Newly hatched larvae are about 1-2 millimetres long and darkish in colour. They grow fast and their arched backs soon turn orange-reddish. Below, on both sides of their thorax run two rows of black spots. A full-grown larva is a little over one centrimetre long.

Evira urges everyone who believes to have seen a Colorado beetle to immediately contact Evira and phone the hotline for sightings of Colorado beetles. Evira will then provide instructions for further measures, if needed. Inspectors at Economic Development, Transport and the Environment Centres (ELY-Centres) answer for the inspections of Colorado beetles. Farmers should not try to eradicate the beetles on their own because it may contribute to the beetles spreading to a larger area. The authorities inspect and destroy Colorado beetle infestations free of charge.

The hotline for reporting the sightings: 040 801 4407 (preferably 10-18 hrs, also in the weekends).

Further information and photos of Colorado beetles:
FAQ The Colorado beetle
www.evira.fi/koloradonkuoriainen (in Finnish)

Further information:
Senior inspector Sari Haikola, Plant Health Unit, tel. 040 687 6641



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