Ikrimah narrates from Abdullah bin Abbas (may Allah be pleased with him) that he said to Ikrimah: "Get up and remove the ticks from this camel." He said: "I am in the state of ihram." He said: "Get up and slaughter it." So he slaughtered it, and Abdullah bin Abbas (may Allah be pleased with him) said to him: "How many ticks, halamahs and hamnanahs do you think you have now killed?"
Abu Ubayd (may Allah have mercy on him) said: Al-Asma'i (may Allah have mercy on him) said: When a tick is at its smallest it is called a qamqamah; when it grows bigger it is called a hamnanah; and when it becomes large it is called a halamah. He said: What is meant by this is that Abdullah bin Abbas (may Allah be pleased with him) saw no harm in a person in ihram removing ticks from a camel; and removing ticks means pulling them off with mud or by hand.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10061