Abstract
It is shown that primordial black holes (PBHs) of masses M > 5x10^14 g are able to absorb white dwarfs (WD) completely for the time of their existence, giving rise to formation of black holes of WD mases. The WD absorption is accompanied by up to 10^{52}erg neutrino bursts which could both considerably contribute to the cosmic neutrino flux and open up a new way of PBHs detection, especially effective in placing new constraints on abundance of nonevaporating PBHs with masses M >> 10^15 g.