Common teasel (Dipsacus fullonum L.) and cutleaf teasel (D. laciniatus L.) Eurasian species from Dipsacaceae were introduced into North America in the 1700s and have spread rapidly in the last 20–30 years in the USA. Since 2000 surveys for finding of bio-control agents are being carried out in Europe. Leipothrix dipsacivagus Petanovic et Rector the first eriophyid mite described on Dipsacus spp. was shown to be host specific by previous tests. Morphological and anatomical alterations of D. laciniatus plants infested by L. dipsacivagus were studied under laboratory conditions at the Agricultural University – Plovdiv and under field conditions in several regions in South Bulgaria in 2007-2008. The symptoms of the infested plants observed in the field at different stages were: smaller rosettes, with reddish wrinkled leaves, stunted bolting plants with shortened internodes and deformed reddish leaves. The flower heads were smaller, strongly deformed, without florets and spines resembling pompoms, no seeds were produced. At lab conditions the symptoms of the infested plants were yellowing and senescing of the oldest leaves, the younger leaves were wrinkled and crispy. Anatomical alterations were observed in all leaf layers: upper and lower epidermis, palisade and spongy parenchyma. Further investigations are necessary to prove that the described symptoms in the field are caused solely by the feeding of the mite and not by a plant pathogen.