Not only have consumers coevolved with their food resources, but they have coevolved with them as these resources have been modified by other herbivores and detritivores. Current theory states that most plants respond to herbivory by producing chemical that adversely affect the growth or survivorship of the herbivores. Certain consumers, however, may exhibit positive growth responses when these changes in plant chemistry occur. Increased growth is predicted whenever herbivory increases the quality of the food resource via plant stress or when it removes chemicals having a negative effect on the palatability or assimilation of the resource. I suggest that these positive responses are more widespread than is currently acknowledged