Observations of Colorado Beetles Urgently Required
The latest beetle observations were made in Karjalohja and Loviisa in the Uusimaa region in late July. Earlier beetle sightings in Uusimaa were made in Pornainen and Vihti. Other Colorado beetle infestations are located in Kangasniemi (Southern Savonia), Savitaipale (South Karelia), Kotka (Kymenlaakso) and Salo (Southwest Finland).
Some Colorado beetle larvae have already pupated underground. After pupating, adult beetles emerge and climb onto potato crops, to feed on the leaves and stems before hibernating. The beetles burrow deep into the ground to hibernate and re-emerge the following summer, to feed and reproduce above ground. For this reason, it is vitally important to locate beetle infestations now, in order to eradicate them before the beetles burrow into the ground.
Adult beetles, larvae in different stages of growth and egg batches may still appear on potato crops. The larvae are found in large groups, which eat the leaves almost completely. Groups of larvae and traces of their feeding are easier to see than adult beetles in potato crops. If the crops bear a distinct infested spot, eaten by larvae, but no larvae are visible, this means that the larvae have burrowed into the ground to pupate. After the pupation period, the crops will be infested with several new adult beetles.
A fully grown Colorado beetle measures about one centimetre, with 10 black longitudinal stripes on its yellow back. The beetle’s 1.5-millimetre-long yellowy-orange eggs are found in tight groups on the underneath of the leaves. A newly hatched larva is approximately 1–2 millimetres long and darkish in colour. The larvae grow rapidly, and their convex back soon turns orange to pinkish-red. Larvae have two rows of black spots along both sides. A full-grown larva is just over a centimetre long.
Beetle sightings and suspected sightings should be reported to Evira's service number for observations. Eaten, infested spots should also be reported, because larvae may be pupating underground. Evira will provide further instructions during the phonecall.
Inspections are carried out by inspectors from Evira and ELY-centres. Evira's inspectors also perform eradication measures against beetle colonies. Farmers should not try to destroy infestations on their own, because this may cause the beetles to spread to a wider area. Inspections and eradication are free of charge for farmers.
The service number for reporting observations is +358 (0)40 801 4407 (9 a.m. to 8 p.m., also on weekends).
Further information and images of the Colorado beetle, information on sites where it has been found, as well as instructions for monitoring potato crops and taking action, are available on Evira's website: www.evira.fi/koloradonkuoriainen (In Finnish).
Raija Valtonen, Head of Control Section, Evira, tel. +358 40 560 2510