  The network of cosmic strings generated in a phase transition during
inflation enters the scaling regime later than that of usual strings. If it
occurs after the recombination, temperature anisotropies of the cosmic
microwave background (CMB) at high multipole moments are significantly reduced.
In this paper, we study such effects qualitatively and show that the constraint
on the cosmic string tension from the CMB temperature anisotropies and B-mode
polarizations can be relaxed. It is shown to be difficult to explain the recent
BICEP2 and POLARBEAR results in terms of signals induced by cosmic strings
alone even if we take into account the delayed scaling. However, the
inflationary tensor-to-scalar ratio required to explain the observed B-mode
signals can be slightly reduced to be consistent with the Planck constraint.
