Projector Method


These instructions are for wing measurements to assess cubital indices and discoidal shifts of honeybees for the purpose of determining race and/or purity of mating.  A table of factors is provided elsewhere to which reference should be made for comparison with your results.
A sample of 30 bees is required from each colony to be tested.  The bees. should be dead.

The equipment required is as follows:- A 35mm slide projector, a supply of 3mm glass slide mounts (GEPE), a pair of tweezers and some double-sided sellotape.

Prepare two slides per colony sample by placing 3 narrow strips of sellotape of 2mm width on one half of each pair of slides.  Position these 10mm, 2Omm 30mm from the left hand edge of the slides.  Remove the right wings in turn, and mount on to the 35mm slide, 15 wings to each slide in three vertical columns of five per column, placing the root of each wing on one of the narrow strips of sellotape.  Once the slide has all its wings, snap the other half of the slide in place.  Write the colony reference number on the slide in pencil.

Set the projector up with a slide in it so that the projected image is level, with its side’s perpendicular and with a horizontal width of about 4 feet.  The projection should be on to a wall not a screen, so as to have a firm surface on which to place the measuring cards.  The images of the wings should have the wing roots on the left.

Prepare a note pad on which to enter the results.  The first column being numbered 1 to 30, the second column headed ‘Cubital Index’; the third column headed ‘Discoidal Shift’.  This will suffice for one set of readings.

Taking the cubital readings first, use the cubital measuring fan supplied.  The manner is as shown in the diagrams alongside the fan.  Place the fan over the projected image of the wing, so that the sides of the oblique ladder pass accurately through the joints of the section marked ‘a’ on the lower side of the third cubital cell, and the part of the vein marked ‘b’ lies parallel to, but not necessarily on top of, one of the rungs of the ladder.  Then the position of the joint at the other end of the section ‘a’ and read off on the scale on the bottom of die fan.

Now take the discoidal shift readings using the measuring card supplied.  The horizontal line at the top of the card is placed so that it cuts through the long cell along the leading edge of the wing, intersecting the mid point of each end of the cell as shown in the diagram on the measuring card, and at the same time the vertical line should be positioned so that it cuts through the joint which is approximately halfway along the bottom of the long cell.  Now it can be seen that the discoidal point, which is shown as ‘Di’ on the diagram, can be given a value.  This will be either zero or have a negative or positive number.  This is now entered on the results pad.  Repeat for the remaining wings on the slide.
The whole procedure is repeated for the second slide to give the total of 30 readings of both indices.  These can now be plotted on a scatter gram, using the vertical scale for the cubital indices and the horizontal scale for the discoidal shifts.  Note: – the BIBBA Morphometric Record Card has both a table ready for entry of results and a blank graph to plot the scatter gram.

For the interpretation of the results refer to the table of body characters on the separate sheet, and also the book, “Breeding Better Bees”, by E.Milner & J.Dews.

It should be noted that a tight pattern on the scatter gram indicates a pure race of bee, and a loosely scattered pattern indicates a mongrel or hybrid bee.

Prepared and edited from various sources by Albert Knight.

“Breeding Better Bees Using Simple Methods”,
by John E.Dews & Eric Milner
“The Dark European Honey Bee”,
by Prof. Friedrich Ruttner, Eric Milner and John E. Dews

The first of the above books has the necessary measuring devices included in a pocket inside the back cover, and there are good descriptions on how to use this method.
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And read the following article in full.
An introduction to understanding honeybees, their origins, evolution and diversity
by Ashleigh Milner