Recent research results in New York and Pennsylvania have shown that the entomopathogenic nematode Heterorhabditis bacteriophora ‘Oswego’ has a significant impact on the populations of corn rootworm, clover root curculio and alfalfa snout beetle and will persist in field plots for more than 5 years from a single inoculation. The availability of an effective persistent nematode “opens the door” for augmentation rather than the historical “biopesticide” approach of inundative releases. This study monitors the population changes of established nematode populations when the cropping system is changed from continuous corn to other typical rotated crops on the dairy farm.