As noted earlier in this massekhet, although many agricultural activities are forbidden on Hol HaMoed and during the Sabbatical year, those tasks that are essential for the ongoing upkeep of fields are permitted. One example presented in the last Mishna on our daf is the need to destroy pests that would otherwise damage the plants and fields.
The example presented by the Mishna is the need to trap ishut and akhbarim. The Gemara appears to know that akhbarim are mice. What are ishut? Rav Yehuda claims that they are creatures without eyes. Although this description sounds strange, it is actually not difficult to identify the animal discussed in the Mishna. It is likely a type of spalax – a blind mole rat – and specifically the spalax ehrenbergi, which is the most common type found in Israel. This rodent, with a round body covered with gray fur, grows to a length of 12-25 centimeters. Since its small eyes are covered by fur from birth, it is blind. This creature lives underground where it digs the burrows in which it lives. It eats the roots of plants and can do serious damage to produce.
The Gemara quotes a baraita that offers another example of a pest. Ants do occasionally damage crops, and it is necessary to destroy anthills in order to protect the field. Rabban Shimon ben Gamliel teaches that the suggested method of controlling the ants is to bring a clod of earth from another field, place it on top of the existing anthill, and the ants will destroy one another. This method works because every anthill has a particular odor, which develops from the type of earth, the food that is brought in, the remains of dead ants, etc. Ants recognize one another based on this particular smell and from bodily secretions. When a “foreign” ant enters an anthill, he is taken for an enemy and is killed by the ants protecting their home.