Cherries

I have a row of 3 dwarf cherry trees, more or less espalier form.  When they blossomed last year, I saw very few bees about, but left them to get on with it - and had six, yes 6, cherries.  I didn't bother to net them,  This year, again no bees visible.  I did a wee experiment; I went out with a brush and tickled the flowers - but on one side of the row only.  I now have bunches of fruit swelling quite nicely on that side of the trees, but practically none on the other, only unfilled wizened little shapes. The couple of half-hours I spent on them really made a difference.  I netted them yesterday, and hope for a reasonable crop.