Target pest: Asterodiaspis quercicola (Homoptera: Asterolecaniidae), pit scales
Agent introduced: Habrolepis dalmanni (Hymenoptera: Encyrtidae)
Import source: Massachusetts, USA
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.