The annihilation of dark matter particles captured by the Sun can lead to a 
neutrino flux observable in neutrino detectors. Considering the fact that 
these dark matter particles are non-relativistic, if a pair of dark matter 
annihilates to a neutrino pair, the spectrum of neutrinos will be 
monochromatic. We show that in this case, even after averaging over production
 point inside the Sun, the oscillatory terms of the oscillation probability 
do not average to zero. This leads to interesting observable features in the 
annual variation of the number of muon track events. We point out the 
possibility of studying the initial flavor composition of neutrinos produced 
by the annihilation of dark matter particles via measuring the annual 
variation of the number of muon-track events in neutrino telescopes.