Studies on occurrence and harmfulness of celery fly on Sosnowski’s hogweed plants were performed in 1999–2002 in three plots at Minikowo, Mochełek and Topolno. At Mochełek, Minikowo and Topolno 40.65, 39.42 and 32.14% ofleaves, respectively were occupied by generation I ofthe fly while 14.8, 18.12 and 10%, respectively by the generation II. Most mines were caused by generation I in 2000 and 2002 at Minikowo and Mochełek. Generation II was characterized by a low population density in all plots.
The research into the occurrence of herbivorous heteroptera of Orthops genus on Sosnowski’s hogweed (Heracleum sosnowskyi Manden.) was carried out over 1999–2002 in the vicinity of Bydgoszcz. The analysis of the faunistic material collected of Heteroptera order showed the occurrence of 3 species where dominant heteroptera were represented by: Orthops campestris L. (48.57%) and Orthops kalmi L.(44.91%), while Orthops basalis Costa was scarce. The maximum abundance of these species coincided with full flowering and the beginning of hogweed fruit formation.
The paper presents the results of a study on mericarps and seed morphology of four taxa occurring in Poland: Heracleum sphondylium subsp. sphondylium and subsp. sibiricum, H. mantegazzianum and H. sosnowskyi. Apart from selected biometric traits we analysed pericarps and seed-coat patterns using a stereoscopic microscope (SM) and a scanning microscope (SEM). Considerable diff erences in the dorsal surface of mericarps were observed, but major structural similarities were found on the ventral surface of mericarps. Pericarp surface diff ers signifi cantly between native and alien taxa in terms of secondary sculpture. The examined seeds were characterised by reticulate primary sculpture with diff erent size and shape of testa cells. The macro- and micromorphological characteristics of the mericarp and seeds may provide valuable additional diagnostic criteria for delimitation of Heracleum and can be used in the identifi cation of fruits and seeds.
In 1998 and 1999, the research on the contents of entomofauna settlement of Heracleum Sosnowskyi Manden was carried out at Mochełek, and in 1999 - at Minikowo near Bydgoszcz. Useful insects were the most abundant group in the tested habitats. Based on the results of the investigations, it can be concluded that only two species: blunt’s flat-body (Depressaria depresella Hb.) and celery fly (Phillophylla heraclei L.) may be of any importance in the fight against population of this plant.