Larvae of Inachis io were fed with pollen of transgenic maize (event Bt-176) in no choice tests, by applying pollen to leaves of nettle plants (Urtica dioica). Compared with the untreated control, 2nd instar larvae showed a significantly increased mortality of 62,3%, if they received 80 pollen grains of the transgenic cultivar Pactol CB. Even a low dose of 10 pollen grains per larva caused a distinct reduction in weight gain. LD50 value for 2nd instar larvae was calculated as 61,4 pollen grains (95% confidence limits: 29,3 to 88,7). 3rd and 4th instar larvae, on the other hand, didn't show an increased mortality, if they consumed 80 pollen grains. However, these caterpillars only reached 75,6% weight gain, compared with untreated individuals. Pollen from the non transgenic hybrid Pactol didn't harm either younger or older larvae, even it was consumed in extremely high doses. Finally it is discussed, if it is possible to reduce negative effects of Bt-maize cultivation on Inachis io populations by using cultivars with low toxin expression in the pollen or by planting non-transgenic maize around Bt-corn fields.