In August of 2007 and 2008, a field investigation was made to study the relationships among Cyrtotrachelus buqueti larval density and wormhole number and bamboo shoot damage degree in Sichuan Province. The three pairs of variables, i. e., C. buqueti larval density and wormhole number, C. buqueti larval density and bamboo shoot damage degree, and C. buqueti wormhole number and bamboo shoot damage degree, fitted cubic equations well, with the correlation coefficients at P = 0.001. Based on these mathematical models, the forecast tables for C. buqueti larval density and bamboo shoot damage degree were established, and the thresholds of C. buqueti larval density and wormhole number were 0.13 and 0.40 individual per bamboo, respectively.