  The nature and the location of the lenses discovered in the microlensing
surveys done so far towards the LMC remain unclear. Motivated by these
questions we compute the optical depth and particularly the number of expected
events for self-lensing for both the MACHO and EROS2 observations. We calculate
these quantities also for other possible lens populations such as thin and
thick disk and galactic spheroid. Moreover, we estimate for each of these
components the corresponding average event duration and mean mass using the
mass moment method. By comparing the theoretical quantities with the values of
the observed events it is possible to put some constraints on the location and
the nature of the MACHOs. Clearly, given the large uncertainties and the few
events at disposal it is not possible to draw sharp conclusions, nevertheless
we find that certainly at least 3-4 MACHO events are due to lenses in LMC,
which are most probably low mass stars, but that hardly all events can be due
to self-lensing. This conclusions is even stronger when considering the EROS2
events, due to their spatial distribution. The most plausible solution is that
the events observed so far are due to lenses belonging to different intervening
populations: low mass stars in the LMC, in the thick disk, in the spheroid and
possibly some true MACHOs in the halo.
