Target pest: Asterodiaspis variolosa (Homoptera: Asterolecaniidae), pit scales, golden oak scale, pustular scale
Agent introduced: Habrolepis dalmanni (Hymenoptera: Encyrtidae)
Import source: Massachusetts, USA (possibly Washington 1923)
Release details: 9 adults were released in Christchurch in 1923 and 159 in 1928. There were releases in Nelson from 1924 -28 (152 in insectary and 464 in the field). Redistributed from 1929 to 1938
Establishment: Established and spread quickly
Impacts on target: Caused an apparent improvement of oak tree health but pit scales are common and still cause damage.
Cameron PJ, Hill RL, Bain J and Thomas WP (1989). A Review of Biological Control of Invertebrate Pests and Weeds in New Zealand 1874-1987. Technical Communication No 10. CAB International Institute of Biological Control. DSIR Entomology Division. 424p.
Tillyard RJ (1923). History of the introduction of beneficial insects into New Zealand. Proceedings of the Pan-Pacific Science Congress, Australia, 383-390.