Recent research on poplar defoliators and sap-sucking insects revealed presence of Lispothrips crassipes, a new pest in Croatia. During a ten year period it fluctuated in population density and about 44 hectares of poplar cultures have been destroyed since its first finding.
In 1990 two experimental treatments were made with four insecticides. Due to a late after-treatment inspection and lack of knowledge about thrips biology, suppression success was not satisfactory. Among applied insecticides, Feniton-50 EC (a.i. fenitrotion) and Lebaycid EC 50 (a.i. fention) appeared to gain better thrips control. Insect development was monitored in 1994 and 1995 when population was low in density. Thrips related damages could not been evaluated. At present state of knowledge it is characterized as secondary in nature, attacking weakened, stress-preconditioned poplar trees, and being detrimental only in large numbers.