nail gall
noun
1- a small conical nail-shaped gall which forms on the leaves of lime trees in response to the presence of mites（螨在欧椴树叶上形成的）钉头瘿。
1.1
- The mite is Eriophyes tiliae, family Eriophyidae.该螨为椴叶绒毛瘿螨, 瘿螨科。