Hosny, M.M. 1968 Classification of certain insect pests of Egyptian agriculture into three types of time-relative population trends.. Bulletin de la Societe Entomologique d'Egypte 52: 179-182.

Notes: When considered over a relatively long period such as 20 or 30 years, populations of some insect pests can be seen to remain at a relatively constant level, despite even large fluctuations in individual years. In other species, however, there may be a pronounced increase or a pronounced decline in population over such a period. The author has found that in Egypt, arthropods of which populations have shown signs of gradual increase in Egypt over 10-20 years are stated to include Icerya purchasi Mask. and Aonidiella aurantii Mask. Steady decreases in population occur somewhat rarely, but integrated control measures can produce this effect. In Egypt, populations of Chrysomphalus aonidum have declined steadily over a period of 10-15 years.