Moussa, M.E. 1986 Bionomics, relative abundance and natural mortality rates of the oriental red scale, Aonidiella orientalis (Newstead) in Riyadh, Saudi Arabia (Homoptera, Diaspididae).. Journal of the College of Agriculture, King Saud University 8(1): 227-234.
Notes: The oriental red scale, Aonidiella orientalis is a serious pest of several fruit, ornamental and shade trees in different regions of Saudi Arabia. The insect was reared on mandarin leaves under natural conditions. During the period from Oct. 15, 1982 to June 13, 1983, three generations were recorded. One more generation is expected during the rest of the year, so the insect may have 4 generations per year in the Riyadh region. The mean numbers of eggs laid per female were 29 and 46 eggs for the first (winter) generation and the third (summer) generation respectively. The mean durations recorded for the egg stage, first, second, and third nymphal instars during the first generation were 2.7, 15.5, 26.20 and 11.5 days, respectively. More females than males were produced, and the sex ratio was almost 1 : 2. The population of insects decreased during (Dec. - Feb.) and increased during (Apr. - Jun.). The upper surface of the leaves harboured the majority of insects. The highest mortality rate of females (34.3%) was observed in the third generation and the lowest (14.51%) in the second generation. Four hymenopterous parasites were reported attacking adult females: Comperiella bifasciata, C. aspidiotiphaga, Azotus elegantiulus and Marietta javensis.