Biological control attempts on pome fruit (apple and pear) in North America, 1860-1970.

Biological control attempts on pome fruit in North America, 1860–1970, are summarized and successes and failures reviewed. In all cases, save two, claims in support of successes are lacking. It is concluded that a modern research approach to the study of biological control—including a study of the population dynamics of the host species and of the biotic agent used in control—must be taken. Claims of successes of biotic agents—parasites and predators—in control of pome fruit insect pest populations (stage or generation) must be supported by quantitative multifactor studies. Otherwise the scientific requirements and exigencies (e.g. manipulation of biotic agents with predictability) will not be satisfied.