Tetrastichus planipennisi is a parasitic non-stinging wasp of the family Eulophidae which is native to North Asia.

As part of the campaign against the emerald ash borer (EAB), American scientists in conjunction with the Chinese Academy of Forestry searched since 2003 for its natural enemies in the wild leading to the discovery of several parasitoid wasps, including Tetrastichus planipennisi which is a gregarious endoparasitoid of EAB larvae on Manchurian Ash (Fraxinus mandschurica) and has been recorded to attack and kill up to 50 percent of EAB larvae.

[2] Tetrastichus planipennisi parasitize EAB larvae by drilling through the bark and laying eggs on its host.

[2] Tetrastichus planipennisi, a gregarious larval endoparasitoid, has been introduced and released into the United States of America as a possible biological control of the EAB along with two other wasps, Oobius agrili, a solitary, parthenogenic egg parasitoid, and Spathius agrili, a gregarious larval ectoparasitoid.

Extensive studies on the specificity of these parasitoids on native beetles and other insects has revealed that in laboratory no-choice assays, Tetrastichus attacked only actively feeding EAB larvae in ash branches and rejected all non-EAB species as hosts.