Abstract: In order to overcome the shortcoming of BP neural network,which was easily sinking into partial smallest value,the Genetic Algorithm(GA) was combined with the BP neural network.A new algorithm,the GA-BP mixed model of trained neural network was applied to forecast the occurrences quantity of Masson Pine Caterpillar(Demdrolimus punctatus Walker).The results showed that the model had a satisfied fitting and forecast precision.

Key words: Masson pine caterpillar(Demdrolimus punctatus Walker), Genetic Algorithm(GA) neural network, Occurrence quantity, Forecast, GA-BP mixed model