Investigation on cabbage stem weevil (Ceutorhynchus pallidactylus) and rape stem weevil (Ceutorhynchus napi) bionomy was done on two sites in Vojvodina province, Serbia. One of them, Rimski šančevi, is located in the southern part, and the other, Crvenka, in the central part of Bačka region. The species were monitored from 2011 to 2013 using yellow water traps method (Moericke dishes), sweep netting and visual method. The yellow water trap method was the most efficient, yielding 73% of the total collected specimens, followed by the sweeping method, with 17.5% of sampled specimens, while the visual method gave the poorest results with 9.5% of specimens. In total, 1007 specimens were collected, 530 of which at Rimski šančevi (285 cabbage stem weevil specimens and 245 rape stem weevil specimens) and 477 at Crvenka (117 cabbage stem weevil specimens and 360 rape stem weevil specimens). The cabbage stem weevil was more abundant at Rimski šančevi while the situation was inverted in Crvenka where rape stem weevil was more common species. Males and females appeared synchronically at both localities. The sex ratio was approximately 1:1, with variations between sites and year. The beginning and the end of the flight period, as well as its maximum, were determined for the two species in both sites during every year. Both species usually resume their feeding activities starting from the middle of March, while maximum flight usually occurs at the beginning of April. In the second half of April activity declined. The occurrence of the new generation was recorded in the second half of May and beginning of June. The potential harmfulness of both species to oilseed rape was estimated using isolation cages during 2012 and 2013 with different combinations of both species. Although there were significant statistical differences (P˂0.05) between variants for plant height and first lateral raceme height parameters, no specific correlation with certain variant was obtained. The highest mean number of damaged leafs was recorded in cages with one cabbage stem weevil on five plants (CSW 1/5).Ispitivanje bionomije male repičine pipe (Ceutorhynchus pallidactylus) i velike repičine pipe (Ceutorhynchus napi) obavljeno je na dva lokaliteta u Bačkoj, Vojvodina, Srbija. Jedan od lokaliteta, Rimski šančevi, nalazi se u južnom delu, a drugi, Crvenka, u centralnom delu Bačke. Brojnost vrsta je praćena upotrebom metoda žutih lovnih posuda (Merikovi sudovi), sakupljanjem kečerom i vizuelnim pregledom, tokom sezona 2011-2013. Najefikasnija je bila metoda žutih lovnih posuda sa 73% od ukupno uhvaćenih jedinki. Na drugom mestu je metoda izlovljavanja kečerom (17,5%) a na trećem vizuelna metoda (9,5%). Ukupno je uhvaćeno 1007 jedinki od kojih 530 na lokalitetu Rimski šančevi (285 jedinki male repičine pipe i 245 jedinki velike repičine pipe) i 477 jedinki na lokalitetu Crvenka (117 jedinki male repičine pipe i 360 jedinki velike repičine pipe). Mala repičina pipa je bila brojnija na lokalitetu Rimski šančevi dok je na lokalitetu Crvenka brojnija bila velika repičina pipa. Mužjaci i ženke obe vrste su se javljali skoro u isto vreme. Seksualni indeks je iznosio približno 1:1 sa variranjima u odnosu na lokalitet i godinu. Utvrđen je početak aktivnosti, maksimalna brojnost odraslih jedinki kao i završetak aktivnosti na oba lokaliteta tokom svake godine praćenja. Početak aktivnosti, za obe vrste, je uglavnom sredinom marta a maksimum leta krajem marta i početkom aprila. U drugoj polovini aprila brojnost opada. Zabeležena je sporadična pojava jedinki nove generacije krajem maja i početkom juna meseca. Uticaj larvi male i velike repičine pipe na biljke uljane repice ispitivan je u izolacionim kavezima tokom 2012. i 2013. godine u varijantama sa različitim brojem jedinki svake vrste pojedinačno i kombinovano. Iako su postojale statistički značajne razlike (P˂0,05) između varijanti za parametre visina biljaka i visina prve bočne grane, nisu uočene pravilnosti u vezi sa uticajem konkretne varijante na date parametre. Broj oštećenih listova bio je najveći kod varijante sa jednom malom repičinom pipom na svakih pet biljaka uljane repice (MRP 1/5) a nešto manji u varijantama sa jednom malom repičinom pipom na svakih osam biljaka uljane repice (MRP 1/8) i obe vrste na svakih pet biljaka (VRP+MRP 1/5)..