Colorado beetle season about to start
The closest permanent populations of Colorado beetles are found south and east of Lake Ladoga in Russia. The adult Colorado beetles that have burrowed into the ground come out of hibernation when the temperature of the soil exceeds 15 degrees. This usually happens at the end of June and beginning of July. If the amount of beetles hibernating in a particular area is large, they will migrate to new areas in search of better feeding grounds. The beetles are poor fliers, however, and need favourable air currents to travel over larger distances.
Colorado beetles occur commonly in the Baltic countries and in Russia, so air currents and thunderstorm fronts from the east and south-east, in particular, add to the risk of them drifting to Finland. In addition to the air currents, the beetles can be carried to Finland on cars and trains to a minor extent. The risk of a Colorado beetle invasion is highest in South Karelia, North Karelia and South Savo, but thunderstorms can carry the beetles also to other parts of Finland. The plant protection inspectors of Evira and the Centres for Economic Development, Transport and the Environment start their inspections after mid-July.
An adult Colorado beetle is about one centimetre long. There are 10 black longitudinal stripes on the yellow back and the pronotum is orange with black spots. The beetle’s semolina sized yellow eggs are in tight groups on the underneath of the leaves. The larvae are orange in colour with black spots in two rows on both sides. The larvae do not appear until the turn of July-August.
The adult beetles and larvae first eat holes in the potato leaves and later eat the leaves almost completely, making them easy to detect. In the home garden there are many other common insects that eat the leaves of plants. The Colorado beetle only eats the leaves of potatoes and other solanaceae.
Hot line for reporting of findings in Finland (9 am. to 8 pm.): +358 40 801 4407.
Unless a specific need arises, Evira will issue the next Colorado beetle communication on 14 July 2010.
For more information, please contact:
Atro Virtanen, Senior Officer, tel. +358 (0) 2077 25047
Raija Valtonen, Section Head, tel. +358 (0) 2077 25040