  In this comment, we analyze the mathematical model by Holst et al that
estimates the increased mortality of Inachis io larvae caused by Bt-maize
pollen in European farmaland. In particular, we focus our attention on the part
of Holst et al's work that models the Bt-maize pollen loss on plant leaves by a
differential equation. We provide the exact solution of the differential
equation, showing that the behaviour of the solution, when the time goes to
infinity, is different from what claimed in Holst et al's work.
