Mishnah Taharos 9:8: If a vermin was found among the milling stones [for grinding the olives before they are pressed], only the area it touched is rendered impure. If a liquid was flowing through [all the olives], everything is impure. If it [the vermin] was found on top of the leaves [of the olives], they should ask the press workers to say, "We did not touch [the vermin]." If it was touching the main pile [of olives], even by a hair, it is impure.

הַשֶּׁרֶץ שֶׁנִּמְצָא בָרֵחַיִם, אֵין טָמֵא אֶלָּא מְקוֹם מַגָּעוֹ. אִם הָיָה מַשְׁקֶה מְהַלֵּךְ, הַכֹּל טָמֵא. נִמְצָא עַל גַּבֵּי הֶעָלִים, יִשָּׁאֲלוּ הַבַּדָּדִים לוֹמַר לֹא נָגָעְנוּ. אִם הָיָה נוֹגֵעַ בָּאוֹם, אֲפִלּוּ בְשַׂעֲרָה, טָמֵא:

Mishnah Taharos 9:9: If it [the vermin] was found upon those [clusters of olives] that were separated [from the main pile, and placed upon it], if it is touching [a cluster] the equivalent of an egg [in volume], it is impure. If those [clusters] that were separated were [placed] upon others that were separated [and not upon the main pile], even though it [the vermin] is touching the equivalent of an egg [in volume], only the area it is touching is impure. If it was found between the wall and the olives it [the pile] is pure. If it was found on the roof, the [contents of the] vat is pure. If it was found in the vat, the [contents of the] roof is impure. If it was found burnt on top of the olives, and similarly a [impure] piece of cloth that was worn out, [if it was found on top of the olives,] it is pure, because all impurities are [determined] in accordance with [their status at] the moment they are found.

נִמְצָא עַל גַּבֵּי פְרוּדִים, וְהוּא נוֹגֵעַ בְּכַבֵּיצָה, טָמֵא. פְּרוּדִים עַל גַּבֵּי פְרוּדִים, אַף עַל פִּי שֶׁהוּא נוֹגֵעַ בְּכַבֵּיצָה, אֵין טָמֵא אֶלָּא מְקוֹם מַגָּעוֹ. נִמְצָא בֵין כֹּתֶל לַזֵּיתִים, טָהוֹר. נִמְצָא בַגַּג, הַמַּעֲטָן טָהוֹר. נִמְצָא בַמַּעֲטָן, הַגַּג טָמֵא. נִמְצָא שָׂרוּף עַל הַזֵּיתִים, וְכֵן מַטְלִית מְהוּהָא, טְהוֹרָה, שֶׁכָּל הַטֻּמְאוֹת כִּשְׁעַת מְצִיאָתָן: