Emergence pattern of Balaustium murorum (Acarina: Erythraeidae) on concrete block walls

Abstract

The erythraeid mite, Balaustium murorum, is a nuisance in urban areas of Japan because of its mass emergence. To know the temporal pattern of the emergence, the numbers of mites at each developmental stage were counted on the surfaces of concrete block walls in Chiba Prefecture. The mites appeared for approximately 90 days from mid-March to mid-June. The peak numbers of larvae, nymphs, and adults were observed in mid-April, late April to early May, and mid-May, respectively. The emergence periods of all three stages were almost identical, at approximately 40 days. Nymphs were observed with larvae or adults, but larvae and adults were not observed together.