Q. I was recently cleaning a functioning Aron Kodesh and found a picture of a Rebbe inside. I was told that it was a picture of Rav Shaya of Kerestir and it was important that it be visible (in the pitch dark Aron Kodesh when closed) as it keeps away the mice.
I remarked that it reminds me of the idol that Menashe HaMelech put in the Kodesh HaKodoshim, and that the Cristians also have patron saints that they believe chase away mice and maybe a picture of them would be effective. I was criticized for making light of something I did not believe in. I replied that I thought the decree of Chazal that Kisvei HaKodesh conveyed ritual impurity to the hands was supposed to keep away the mice.

Is this a real segulah or Darkei Emori?
Is one allowed to put a picture in the Aron Kodesh for this or any other purpose?
If the decree of Chazal is not enough to keep away the mice, are there other Segulahs to use or perhaps we are deficient in some spiritual way and Hashem is trying to send us a message, which we have been unable to decipher. Perhaps the Rav can direct us.

A. Other similarly puzzling segulos are mentioned in seforim for mice protection. Divrei Sholom (quoted in Zeicher Osso 10: n. 238) mentions placing the shirayim or food leftovers from a tzadik. It also helps for memory loss, reflecting and contrasting the effects from eating leftovers from mice. (Horiyos 13b) Another segula for mice defence is being careful with m’aaser contributions. (ibid.) Sipurei Tzadikim (p. 18) quotes that the Yismach Moshe would give kemios and amulets to be placed in the mice affected locations.
Placing the picture of Rabi Yeshaye Steiner from Kerestir is indeed mentioned in seforim (Rina Veyeshua Beoholei Tzadikim, et. al., some seforim include a picture too.) Apparently this segula is already well known and established in some circles.
Many segulos are recorded in the Talmud and other seforim and much has been written about the propriety and correctness of following and using them.
Horav Shlomo Miller’s Shlit’a opinion is that in the end it all depends on one’s family traditions and in the mind and intuition of the beholder.
Mishna Berura (154: 31) mentions the prohibition of placing extraneous objects inside the Aron Hakodesh. However, he quotes Magen Avraham, that in regards to yerios we use the principle of “Lev bais-din masne aleihem” or the Aron was created from it’s onset with the condition of permitting this use. Hatefila Vehichateha (p. 138) quoting Yabia Omer (8: 19) and other Poskim, permits placing inside the Aron hakodesh wine for a segula and on the doors the tefilos recited when opening the Aron.
Horav Shlomo Miller’s Shlit’a opinion is that, similarly if this shul follows and maintains already the tradition of placing the above picture for protection, it would be permitted.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a