Two pests have become sufficiently troublesome in south Florida to require attention. One, the papaya fruit-fly (Toxo-trypana curvicauda Gerst.) threatened at one time to become serious. This insect occurs in several parts of tropical America. The female inserts her eggs into the immature papaya by means of a long ovipositor, and the larvae first feed in the central seed-mass, but later work into the flesh of the fruit, frequently rendering it unfit for human consumption. The only means of control which have been suggested are the destruction of wild plants and infested fruits, and the production of varieties having very thick flesh, so that the ovipositor will not reach to the seed-cavity (the young larvae are unable to live in the flesh). A fungous disease known as papaya leaf-spot (Pucci-niopsis caricoe Earle) frequently attacks the foliage in the winter season, forming small black masses on the under-surfaces of the leaves. It is not very destructive and is easily controlled by spraying with bordeaux mixture.

In Hawaii a red mite (Tetranychus sp.) sometimes occurs in scattered colonies on the lower surfaces of the leaves and on the fruits. The larvae of a moth (Cryptoblades aliena Swezey) feeds under a web on the floral stems and beneath the flower-clusters. Neither of these pests is said to be serious. The Mediterranean fruit-fly (Ceratitis capitata Wied.) attacks the fruit; its presence in Hawaii has made necessary a quarantine order prohibiting the shipment of papayas from that territory to the mainland of the United States. Two scale insects, Aspidiotus destructor Sign. and Pseudoparlatoria ostriata Ckll., are reported on the plant in Africa and Cuba respectively.