Coates Palgrave, J.A. 1974 Some notes on the pearly scale, Sphaeraspis salisburiensis (Hall, 1940) (Homoptera: Margarodidae).. Arnoldia (Rhodesia) 7(8): 1-8.

Notes: The author describes the previously unrecorded egg and first-instar nymph of Sphaeraspis salisburiensis (Hall). The second-instar nymphs (known as pearls or cysts) and adult female are also described; males are not known. In some areas in Rhodesia, this Margarodid has become an important pest of maize, sugar-cane and Pennisetum clandestinum (which is used for grass lawns). When infestation is severe on maize, the plants are stunted and few ears are produced. Severe infestation of P. clandestinum causes almost complete die-back. When cysts were collected in the field in August and kept either in a glass tube or in soil that was kept watered, long tubular waxy filaments capable of holding water were produced from the pores after about a month, and adults appeared in October. It is thought that there may be a period of diapause terminated by changes in temperature or humidity or both. The adults, which have no mouthparts, were mobile and after moving to the soil surface they re-entered it to oviposit. Eggs were expelled into a case of waxy filaments. On hatching, the nymph moulted and then attached itself to a root, where it presumably remained, overwintering as a cyst. Dimethoate, diazinon, monocrotophos and ethylene dibromide have been used with some success to control infestations in lawns, but the large amount of water required for this type of treatment makes it unsuitable for crops. It is suggested that a rotation including one year of a non-graminaceous crop is the most promising measure to interrupt the life-cycle.