  In theories with cosmic strings, a small fraction of string loops may
collapse to form black holes. In this Letter, various constraints on such
models involving black holes are considered. Hawking radiation from black
holes, gamma and cosmic ray flux limits and constraints from the possible
formation of stable black hole remnants are reanalyzed. The constraints which
emerge from these considerations are remarkably close to those derived from the
normalization of the cosmic string model to the cosmic microwave background
anisotropies.
