Obscure mealybug - Life cycle

The obscure mealybug completes 2-3 generations per year depending on temperatures. In the major apple growing regions of Hawkes Bay and Nelson, where obscure mealybug is most important, there is a two generation life cycle. It overwinters under the bark of the deciduous pipfruit trees, and on a range of other host plants. These include evergreen, deciduous, perennial and annual hosts in the sward or surrounding shelter-belts or 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. Mortality is very high through winter and early spring, but a few mealybugs - usually the first instars (crawlers) - survive and disperse to feed on young leaves at budburst. These mealybugs reach adult in October and November and a 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 obscure 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 obscure mealybug.