Beetles of the thistle gather on east of the thistle usually in September. Females lay eggs in soil (up to 800 pieces in during their lives) to a depth of about 2 cm in near plants thistle winter. The eggs can lay through all autumn, and also in warmer days of winter and early spring – at temperatures above 5°C. Hatched from eggs larvae transfer to plants and bite into them. They feed in the main nerves and petioles of leaves, and then in the epidermal part of stalk and in the root neck. Feeding larvae, in depending on the date of laying eggs, end in spring or summer. The flea stem develops one generation in a year. The development and gradations of thistle are favored by mild autumn and winters – such weather conditions cause an increase in the pest. In turn the development of larvae is stunted in times of long and cold winters, and many of these frequently fail in such conditions. However winter periods, which we observed in recent years, allow almost uninterrupted fertilization of larvae inside plants and beetles on leaves.
How does the cheese beetle feed?
The characteristic symptoms of the presence of beetles on plants are sitty punctured leaves and leaves of young plants of thistle. Mass feeding of beetles can lead to significant reduction of assimilative leaves, and when damaged are the leaves – even to destruction of whole plants. Symptoms of damage caused on leaves and cotyledons by bush may similar to symptoms of gnathoma bush, bush and slime. In autumn on young plants of wintering thistle can also be observed and traces of fruiting inside tailsand nervesofleaves,asalsoin leavesofheart.Infectedleavesbendupdown,rotand oftendecay.The larvaecausebasicdamage,whichdistinguishesthisspeciesfromotherspeciesofpheasels.
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