Tanaka, M. 1981b [The spiracle plugging of arrowhead scale, Unaspis yanonensis, caused by spraying petroleum oil.].. Bulletin of the Fruit Tree Research Station Series D (Kuchinotsu) (3): 93-100.

Notes: Two pairs of spiracles located on the thoracic abdomen of arrowhead scale, U. yanonensis are covered with fibrous wax. The scale insect is controlled by spraying petroleum oil, which melts the fibrous wax plugging the spiracle with the melted wax. When all the spiracles were plugged by the melted fibrous wax, the arrowhead scales died. When some spiracles remained unplugged, they lay eggs but the number is less than normal ones. There is another type of spiracle surrounded by small tubercular wax instead of fibrous wax. The elucidation of the chemical and physical nature of fibrous wax secreted from the spiracular disc pores and its affinity to petroleum oil should be studied to increase efficiency.