thyridium
noun
thy·rid·i·um
-dēəm
plural thyridia
-ēə
1
: a pale spot in the wing vein of some insects especially of the orders Hymenoptera and Trichoptera
2
: one of a pair of oval pits on the second abdominal tergite of some hymenopterans
Word History
Etymology
New Latin, from Greek thyridion window, diminutive of thyra door