In the present paper, the transient properties of an insect outbreak model driven by correlated multiplicative and additive Gaussian noises are investigated. By using the Fokker-Planck equation and the fast descent method, the mean first-passage time, that is the mean reproduction and decline time, is analyzed. The numerical results show that in the process of restraining the expansion of the insect population, the increase of the correlation noise strength makes a positive contribution to the disinsection, and, meanwhile, the appropriate multiplicative and additive noise intensities can also play an encouraging part. During the process of killing a large number of insects, the effects of different noises are different or even contrary.