This topic was pretty well flogged on BEE-L five or six years ago. I got this stuff there:
Eva Crane wrote:
"Where colonies of both Africanized and European bees are present, it is very important to be able to distinguish between them. A simple and rapid method ... is to make three measurements across the parallel sides of 10 cells of natural worker comb; results (Rinderer, 1986) predict that an average of 49 mm [cell size 4.9 mm] or less indicates comb built by Africanized honey bees, and of 52 mm [cell size 5.2 mm] or more, by European bees. Identification is not possible if the distance is 50 to 51 but Africanization might be suspected."
Marla Spivak spent much time in Costa Rica observing the onset of Africanization. She measured the cell size of the European bees before, during and after the arrival. She refers to data collected by researchers as early as 1973 indicating European bees in the tropics built cells ranging from 5.0 to 5.4 mm. These bees, being kept in box hives for centuries, can hardly said to be affected by manufactured comb foundation.
Africanized bee cells were found to be in the range of 4.6 to 5.0 mm, throughout South America. (In Africa, scutellata ranges from 4.7 to 4.9.) According to Spivak, European bees in Costa Rica in 1984 built comb with cells measuring 5.3 mm. When African bees entered the area the numbers immediately fell to 5.0 mm. Later, the range for African bees was shown to be 4.7 to 5.1.
Spivak refers to one apiary that she studied in the mountains. There were 9 hives, which the owners filled with swarms. These hives were plain boxes filled with natural comb. The AVERAGE cell size in each and every hive was 5.3 mm. The first arriving hybrid African swarms built comb around 5.0 mm and subsequent swarms (less hybridized) ranged from 4.7 to 5.0. This phenomenon was observed throughout South and Central American and is fully documented in the book she edited.
She emphasizes that while cell size is a clear indication of Africanization, these bees do not necessarily exhibit the fierce behavior normally associated with this bee type. Even bees with cells as small as 4.7 mm were not always extremely defensive.
* * *
TABLE FROM
BEES AND BEEKEEPING
By Eva Crane, OBE, Dsc (former director of IBRA)
Published By Heinmann Newnes, 1990
ISBN 0 434 90271 3
All Dimensions in mm,
D/W is the ratio of Drone cell size to Worker cell size,
ESW is Excluder Slot Width
Species, Comb Spacing, Cell Size, D/W, ESW
A. mellifera,
European 35a 5.1-5.5 1.3 4.13-4.5
USA --- 5.3b 1.23b ---
A.m.cypria --- --- --- 3.8
A.m.syriaca --- 4.9 --- ---
___________________________________________________
A. mellifera,
African
A.m.unicolor --- 5.0 --- ---
A.m scutellata 32 4.7-4.9 --- 4.4c
A.m. lamarkii 32 4.6 1.33 ---
unspecified
"tropical" 32 4.77-4.94 1.38 ---
in Zimbabwe 32 4.8 --- ---
in Angola,
Tanzania 30-32 4.8 --- 4.35
A.m. capensis 31.8 4.86 --- ---
A.m.litorea 28-30 4.62 1.3 ---
A.m. jemenitica --- 4.75 1.31 ---
A.m.monticola --- 5.0 --- ---
Africanized --- 4.5-5.0 --- ---
__________________________________________________
A.cerana
Japan 30 4.7-4.8 1.13 ---
Nepal 30 --- --- 3.5
India:
Kashmir 35 4.9 1.08 4.0-4.2
d, India:
High Himalayas 30 4.9 --- 4.0
Sub Himalayas 31 4.7 --- 3.75
Central 32 4.5 --- 3.50
South 32 4.3 --- ---
Bangladesh 27-31 --- --- ---
Burma 31 --- --- ---
Java 28 --- 1.17 ---
Philippines 30 3.6-4.0 --- 3.70
___________________________________________________
A. florea
Iran --- 2.9 1.59 ---
Java --- --- 1.55 ---
Oman --- --- 1.50 3.5
Notes
a, 32mm to 38mm is actually used.
b, in USA (Taber & Owens, 1970).
c, this is the gap in square mesh coffee wire, 0.58mm diameter wire on 5mm
pitch.
d, Indian Standards Institution (1976).