Early Quenya
itis
noun. a fly bite
nea
adverb. it is, yes
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
The word ᴱQ. itis “a fly bite” appeared in the Qenya Lexicon of the 1910s derived from the early root ᴱ√ITI “peck, bite (of flies), annoy” (QL/43). Tolkien first wrote this form as itis(s-) implying a stem form of itiss-, but he erased the second s and wrote “(-s)” separately, which seems to imply a stem form of itis-.
Neo-Quenya: I would adapt this word as ᴺQ. itis [þ] based on the Neo-Root ᴺ√ITITH, chosen to preserve Late Quenya s in all forms, and extend its meaning to include both “fly bite” and “✱itch” based on the adjective itisin “itching”.