Pseudaulacaspis pentagona

The white peach scale was first identified by science in 1886 in Italy. However, it is thought to have originated from either Japan or China. It is an armored scale. Since approximately the early 1900's, it has been a serious pest of fruits, especially peach and cherry, in the United States. It is now considered a common pest found in the eastern coastal states of the US, particularly from Maryland southward but it has been previously detected in Massachusetts (Cooley, 1898a). It is also considered a worldwide pest, mainly in tropical and subtropical locations. ScaleNet lists host plants in 90 plant Families, from 253 plant genera. Adult female white peach scales overwinter. In North Carolina, the female will begin egg laying by early April with each female producing over 100 eggs. The number of eggs laid is influenced by the host plant on which the scales are feeding. Egg laying may not begin until late April or May in Massachusetts, depending upon temperature. In points south of Massachusetts, peak egg laying and hatch occurs by the first week in May. This is for the first generation eggs in these locations. Second generation egg laying and hatch can occur in August. If there is a third generation, egg laying and peak hatch occurs in September. Eggs may be laid over a period of approximately 30 days, and subsequently crawler emergence can occur over a similar length of time. Eggs that develop into females are coral colored; those that develop into males are whitish pink. Crawlers, through the end of the first instar, maintain this color difference in males and females. Depending upon their sex, the crawlers undergo 2 (female) to 5 (male) molts or instars. Adult male covers are bright white in color and approximately 2.0-2.5 mm long and elongated. Female adult scale covers are gray, circular, and slightly larger than the males, but often blend in better on the bark of their host plants. When males mature, the bright white coloration may make the infestation appear larger as the scales become easier to see. Males also secrete masses of a cottony substance, which may appear to blanket the host plant bark in snow (Johnson and Lyon, 1991). Females secrete a sex pheromone in order to attract the males to mate. In northern states, there may only be two generations per year. In southern states, there may be up to four generations per year. The white peach scale may be confused with the white prunicola scale (Pseudaulacaspis prunicola), discussed elsewhere in this Guide. In fact, in Massachusetts and other states north of Maryland, it may be more likely that P. prunicola or the white prunicola scale is what is being detected (Miller and Davidson, 2005). The white prunicola scale is a temperate species.