Sanhedrin, 65a: Irrespective of whether they are large or small - even snakes and corpions. See Torah Temimah, note 60.
2)
What is the difference between "Ov" and "Yid'oni"?
1.
Rashi and Targum Yonasan: "Ov" is a kind of sorcery that is called 'Pitum', where one raises a dead spirit
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to under his armpit, from where it speaks; whereas "Yid'oni" places the bone of a Chayah called 'Yado'a' into his mouth, where it speaks by means of sorcery.
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Ramban: And the Torah writes "Sho'el Ov ve'Yid'oni" to include the client in the Isur - though the Ba'al Ov and Yid;oni himself is subject to Sekilah, and the client, only to a La'av - See Torah Temimah citing Sanhedrin, 65a and note 63 & 64.
3)
What constitutes "Doresh el ha'Meisim"?
1.
Rashi: It constitutes either raising a dead spirit on his Eiver, from where it speaks or consulting a human skull.
2.
Sanhedrin, 65b: It constitutes starving oneself before going out to a graveyard so that a Tamei spirit will rest on him.
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