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Additional applications of the Snelgrove Board in honey bee colony swarm control/prevention and use of a double screened board in making vertical splits in early spring
April 2020 1
Last month I wrote about a meth-
od of swarm control/preven-
tion described by Louis Snel-
grove and first published in 19341 that
could be applied before bees started
constructing queen cells. This method
consisted of separating the queen and
flying bees from the nurse bees in a
vertical split. The queen and flying
bees ended up together in the lower
section of the split and the nurse bees
and most of the brood comprised the
upper part of the split. Separation
between the upper and lower clus-
ters was maintained by a few honey
supers and a “Snelgrove board” or
“double screened board” with paired
entrances on three or all four edges
which are manipulated in a series of
“Operations” — as Snelgrove referred
to them — to gradually and system-
atically move bees from one side of
the board (the top) to the other side
of the board (the bottom). Because
the entrances are paired and in close
proximity to one another the bees eas-
ily mistake one for the other.
At regular intervals the entrances
are manipulated so as to trick bees
into using the bottom of a pair of en-
trances after these bees had previously
oriented to the top entrance of the pair.
For example, bees oriented to opened
entrance 1 on the top of the board (see
Fig 1) could be tricked into using en-
trance 2 after entrance 1 is closed and
entrance 2 is opened, which would
lead them to the bottom part of the
split colony below the Snelgrove
board. This separation of bees dimin-
ished the swarming impulse because it
gave the queen ample comb in which
to lay in the bottom colony and main-
tained the nurse bees in the top colony
with no queen and thus no ability to
swarm. I discussed how this setup
can be used to raise new queen cells in
the top colony, to set up a two-queen
vertical system by later replacing the
Snelgrove board with a queen exclud-
er, to eventually split the top colony
from the bottom colony completely, or
to recombine the top colony with the
bottom after the swarming impulse/
season had passed. The essential fea-
ture of this so-called Method I is that
it must be performed before the con-
struction of queen cells. Once the bees
begin to construct queen cells it is very
difficult if not impossible to quell that
instinctual drive to reproduce, and if
one were to place the queen and some
brood in the bottom box of the split,
and the nurse bees and open brood
in the top part above the Snelgrove
board, the bees in the bottom would
continue to construct queen cells and
swarm anyway.
Snelgrove carried out his Method I
(described in last month’s article) on
Fig 1. showing Snelgrove’s original diagram of the board that now bears his name.
Note the paired entrances which are systematically opened and closed to move bees
from above to below at regular intervals. (Use the Fig 1 from the March issue with
“Front” added.)
Part 2 of 2
American Bee Journal2
two colonies which had already pre-
pared queen cells (this was when he
was in the experimental phase with
his board and did not yet understand
how this all worked and how the bees
would react), moving the queen cells,
with the majority of the brood (open
and capped), up top without the
queen. Before he employed his board,
he believed that he needed only to
use a queen excluder directly below
the upper colony, and a few honey
supers between the lower colony and
the queen excluder for the first 3-4
days after he created the vertical split.
As everyone knows, a queen will not
cross a honey super, never mind a
few, right? Fortunately for him, and
this swarm control method, his bees
did not read the same books he was
reading, and on a few occasions he
came back to inspect a few days af-
ter creating the split and found that
the queen from the bottom part of the
split had traversed the honey supers,
squeezed through a gap in the queen
excluder, and had moved into the top
colony of the split. What surprised
him was that not only was the queen
laying in the top split, but the workers
were chewing down the queen cells
he had moved up there.
He thus stumbled upon his Method
II of swarm control, to be used after
the construction of queen cells had
begun. One can see the evolution
of the board in Snelgrove’s mind,
as it is likely that he first separated
the top and bottom bees with only
honey supers and a queen excluder,
but then found the need for a better
way to separate the top and bottom
bees from one another to prevent the
queen from traversing the honey su-
pers and queen excluder and entering
the top colony. Maybe if he had kept
his queen excluders in better repair
and those few queens had not been
able to pass through, we might be
calling this board by a different name,
or not have it at all.
SnelgroveS Method II
As previously stated, this is for
those instances when the bees have
gotten a little bit ahead of you and
have begun to construct queen cells
but have not yet swarmed, so it can
be used for that 8½- or 9-day period
immediately prior to the sealing of the
first queen cell and the issuance of a
swarm. Prior to this, beekeepers had
tried various methods of breaking
down queen cells manually, only to
find that the swarming impulse was
too far advanced and the bees in the
bottom split continued to construct
new queen cells (sometimes as emer-
gency queen cells) after the first queen
cells were destroyed by the beekeeper.
The description of Snelgrove’s
Method II is as follows:
Proceed as in Method I2 but place all
the brood and queen cells, as well as the
queen in the top box labeled A in Fig 2.
Place the broodless combs with bees
in the bottom box B, but with one
comb of sealed brood in the center. It
won’t hurt if there is also some older
open brood, but be sure that there are
no eggs or young larvae less than 4
days old so that the bees in the box,
separated from their queen above,
do not raise a new queen and swarm
despite all your manipulations. If any
of the queen cells are sealed it is im-
portant to place the Snelgrove board
in position as shown in Fig 3. Open
entrance 5 on the Snelgrove board on
the side opposite the entrance to the
lower colony.
Destroy only the capped queen
cells (or move them to another colony
in need, or into a mating nuc; it’s a
shame to waste good queen cells!). If
all the queen cells are uncapped, the
cells capped during the next 24 hours
should be destroyed, or removed and
relocated, the following day.
The foragers will now leave the up-
per box through the open entrance
5 at the back of the Snelgrove board
and return to the front entrance of
box B to which they had previously
oriented. These flying bees now find
themselves in a queenless box (B) and
cannot and will not swarm. The bees
above lose the drive to swarm as there
has been a sudden and dramatic re-
duction in flying bees, and they grad-
ually destroy the queen cells, as some-
Fig 2. showing the order of boxes for Snelgrove’s Method II
when queen cells are not yet capped.
Fig 3. showing how to set up the boxes when capped queen
cells are present.
Fig 4. showing the
final configuration
of boxes and bees.
April 2020 3
how, they magically “know” they will
not be able to swarm. Five days later
close entrance 5 and open entrance 6
of the Snelgrove board to hasten the
movement of newly emerged bees
from the top to the bottom colony.
Open entrance 3 at the side of the
hive to be used by the bees up top.
On the 7th day, or when the queen
cells are destroyed and the queen is
again laying in box A (usually with-
in a week), she and the bees on the
comb on which she is found should
be transferred to the bottom box and
the colony takes the form as shown in
Fig 4. This should look familiar, as this
is how things started in Method I as I
described last month, with the queen
and the flying bees in the lower box,
and the nurse bees and capped brood
above the Snelgrove board. The en-
trances are successively manipulated
so as to move flying bees from above
to below the Snelgrove board. On day
14 close entrance 3, open entrance 4,
and open entrance 1 on the other side
of the hive. This moves even more of
the newly-emerged bees from the top
to the bottom.
This procedure works because it
gets the flying bees to leave box A, and
a swarm cannot develop without fly-
ing bees. Occasionally the queenless
bees below discover the queen above
the Snelgrove board and return to box
A, usually arriving at the entrance to
box B and marching up the outside of
the boxes to the open entrance of box
A, following a route that appears to
be marked by the bees’ tarsal glands.
This difficulty is overcome by remov-
ing box A and placing it several yards
away for two days, preferably on top
of another colony in the apiary, so that
when box A is returned to its place
above the Snelgrove board the few
foragers that will be left behind will
join the other colony and not be lost.
Snelgrove went on to describe sev-
eral other methods of swarm control
in his book, none of which involve the
use of the double screen board which
sometimes bears his name, so I will
only mention that these methods and
their descriptions exist, and refer you
to his book for further reading on the
nitty gritty details of the application
of these other methods.
The Snelgrove board provides a fea-
sible method of controlling swarming
in honey bees provided there are only
a few colonies on which it is applied,
and these colonies are not too far from
the beekeeper’s house, as entrance
manipulations are frequent and many
would consider these swarm control
methods labor-intensive. Each colony
needs attention every 5-7 days for sev-
eral weeks. These methods are better
suited to the backyard beekeeper, and
certainly not to the sideline or com-
mercial beekeeper, who cannot spend
the time required to manipulate en-
trances on such a frequent schedule. If
you want to control swarming early in
the spring and have some fun work-
ing closely with your bees these meth-
ods may appeal to you. Snelgrove
boards can be found for sale by bee
supply houses where they are often
advertised as “double screen boards.”
1 Snelgrove, Louis E., Swarming, Its Con-
trol and Prevention, Northern Bee Books,
Hebden Bridge, 1934.
2 Lehr, Sid, MS, DVM, The Snelgrove
Board: One Method of Swarm Control
With a Few Other Benefits, American Bee
Journal, March 2020, pp. 337-340.
Sid Lehr has been a vet-
erinarian in Palm Beach
County, Florida for over
3 decades, and because
bees are also animals
he is transitioning his
veterinary practice from
diagnosing and treating
disease in cats and dogs to doing the same
in honey bees, which he finds much more
interesting after 30+ years working with the
former. He has post-graduate degrees in
chemistry and veterinary medicine and mar-
vels at what goes on in his little white boxes
on a daily basis.
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ResearchGate has not been able to resolve any references for this publication.