AbstractConventional plant protection procedures and integrated control are being compared in the light of their profitability. Control measures must be based on the density of pest populations. The fluctuations concerned can be usefully reproduced by means of a mathematic pendulum oscillating over a logarithmical scale of the densities. The model shows that better crop yields can be obtained through a reduced application of chemicals. Moreover, the expenditure incurred in integrated control is less and risks of failure are also lower.