Sanhedrin 109a, cited partially in Rashi (17): They would deposit balsam oil with a rich person. He would hide it with his valuables. At night they would track down the smell like dogs, to take his valuables - "Yashuvu la'Erev Yehemu cha'Kelev."

Rashi: Weaker Resha'im who cannot openly rob, they tunneled into houses at night, and during the day they were sealed in their houses.

Malbim: He needs darkness, for then he can tunnel into house; During the day, he makes a sign on the houses that he wants to tunnel into them at night.

Rashi: They did not recognize light - they did not go [outside when there is light].

Malbim: All of these actions are not done in the light, for light harms them.