Thanks a lot for responding to my question on the best way to measure
Sam Droege asked me to summarize your suggestions for the benefit of
the group, so here they are.
The 1st one is from Jim Cane:
The ocular micrometer of a dissecting microscope is perfect for
measuring intertegular span of a bee. You will first need to
calibrate it with a stage micrometer slide, but once done, it is good
The 2nd one is from Jack Neff:
The ocular micrometer in your dissecting scope should work fine for
measuring trans-tegular distances, especially if it has a relatively
fine scale. It probably will be better than a digital caliper for
very small bees. You should remember estimating mass from a single
body measurement assumes a similarity of shape and you can get
significant deviations from this when comparing long skinny bees (like
Chelostoma) with "fat" ones like Xylocopa. In an ideal world, the
best way to compare size is to actually weigh them.
The 3rd is from Anita Collins:
USDA did a lot of bee measuring to identify Africanized specimens vs.
European. We actually did a dissection and projected a part, such as
a leg, o n a digital pad. Software was then used to make the actual
measurement, which was fed directly into a statistical calculation
based on 10 samples.
The 4th is from Charlie Guevara:
Wards Science.com has a slide micrometer for about $15 USD. With that
and the ocular reticule you already have...you can calibrate various
'work-horse microscopes you have'. Be careful of using: 'zoom
magnification adjust' microscopes...you may have trouble knowing
exactly what magnification your using the ocular reticule (ocular
micrometer) with...after hours of 'one of a kind/nonrepeatable'
specimen data record sessions...you may not have exactly the same
zoom-setting on the scope you’re working with!
Thank you all