Citrophilus mealybug - Life cycle

The life cycle of the citrophilus mealybug has not been fully investigated but observations throughout the North Island indicate that it is similar to the life cycle of obscure mealybug. Citrophilus mealybug completes 2-3 generations per year depending on temperatures, and two generations typically occur in the major apple growing regions of Hawkes Bay and Nelson. It overwinters under the bark of the trees, and because of its wide host range, also on perennial or annual hosts in the sward, and on alternative evergreen and deciduous trees and shrubs. The population is a mixture of all stages (instars) over the winter but is dominated by eggs and first instars. There is no true dormancy (diapause). Eggs keep hatching over this period and the young mealybugs feed on warm days. Overwintering mortality is very high, but a few mealybugs - usually the first instars (crawlers) - survive and disperse to feed on young leaves at budburst. These overwintered mealybugs reach adult in October and November and the first generation is completed through December and January. Second generation adults produce eggs from February onwards and this continues into autumn and early winter.

Sexual reproduction is obligatory. While the adult male mealybug lives only 2-3 days, the female may spend 2-3 weeks maturing her eggs and up to two months to lay them. However, >90% of the eggs are laid within the first 10-14 days. The citrophilus mealybug female lays her eggs in an egg sac and the eggs hatch into mobile crawlers. The crawler stage is primarily responsible for dispersal of the population over the host tree and further afield. Mealybugs crawl inside the calyx of apples as soon as there is space, usually from mid-January onwards, depending on cultivar.

Further information is available on the life history of citrophilus mealybug.