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.

Azadirachtin is the most active substance separated from Azadirachta indica. It acts destructively on numerous species of insects and mites. The aim of the presented investigations was to determine the effect of azadirachtin on one of the most dangerous pests of cabbage plants, Pieris brassicae, and on its natural enemy, Apanteles glomerarus. The results of the field observations did not show any repellent effect of azadirachtin relating to laying their eggs cabbage butterflies. However, a significant effect of the azadiraehtin solution on reduction the number of cabbage butterfly caterpillars (it was more distinctly marked in respect to young larva stages) as well as on limited feeding by caterpillars. No negative influence of azadirachtin on a parasite of Pieris brassicae caterpillars, Apanteles glomeratus was distinctly shown.

In 1998 and I 999, the research on the contents of entomofauna settlement of Heracleum Sosnowskyi Manden was carried out at Mochełck, 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 depresel/a Hb.) and celery fly (Phi/lophylla heraclei L.) may be of any importance in the fight against population of this plant.

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.

In the years I 999-2000 the studies on the population of true bugs colonizing the inflorescences of quinoa (Chenopodiwn quinoa Willd.) were conducted in Chrząstowo near Bydgoszcz. The dominating species was Lygus rugulipennis Popp. The species was recorded in 81.44% in 1999 and 83.64% in 2000 of all collected true bugs.

In 1997 and 1998, insects settling cultures of goats rue (Galega orientalis Lam.) at Mochelek were caught. Amongst ground beetles the dominating species were: Pterostichus melanarius lll., Carabus auratus L., Harpalus rufipes De Geer, Harpalus aeneus F., and Bembidion lampros Hbst. and Harp alus frolichi Sturm. were subdominants.