This is a frequently voiced comment:  "I saw lot of them (bees) dead around
(in front of) their hives", and its is usually presented as a question.

I've learned to ask for a definition of "a lot".  To some people, 10 bees
is a lot.

To a commercial beekeeper with lots of strong hives in an apiary, "a lot"
might consist of what one of our guys calls "the sickening crunch" as he
steps through the grass.

A severe pesticide kill will pile up bees over a large area in front of the
poisoned hives.  I've seen cases where you could pick up the bees by the
shovel fulls.  When you walk past a hive like this (and if there is tall
grass in the yard, the drying bodies of the piled up bees "crunch".

I have a suggestion for anyone concerned about dead bees by the hives.
Clear the front of any hive and put down a sheet of light colored cloth
(1-2 meters (yds) square).  Stake down the cloth, and check it every
morning and night.  You may be surprised at how many dead/dying bees are on
the cloth.  Remember also, that you may want to put some border around the
tarp to keep the bodies from blowing off in the wind, and that animals like
skunks may eat the dead bees on the cloth.  That's why checking more than
once a day makes sense.

Strong colonies have 10s of thousands of bees.  A portion of these bees
forage.  Forager bees are the oldest bees in the colony.  Their forager
(flight) life span is relatively short.  If you have good weather and
something for bees to actively gather, a forager may have as few as 10-12
days of flight in its "foraging" lifetime.  In practice, foragers may live
considerably longer, especially when weather condition and resources are
variable (fly one day, not another, etc.).  But, in the midst of a nectar
flow with sunny, calm days; up to 10% of the foragers could die each day of
old age/natural causes.  Now, some die in the field, some get lost, others
become food for a predator, etc.  But some make one last trip to the hive
and perish.  And, they are then tossed out by hive bees.

Now, if you really do have "a lot" of bees on the ground - what are the
causes?

These could be varied, but include pesticides, mites, disease, heat stress
- usually after moving hives, pollution.

Cheers

Jerry