1925] Wing Veins of Bees as Strengthening Elements 
39 
WING VEINS OF BEES AS STRENGTHENING 
ELEMENTS. 
Charles Robertson, 
Carlinville, Illinois. 
Lutz (1, 182-3) says that if the wing- veins of bees have a 
function it is probably to strengthen the wing. “However, the 
'stingless honey-bees’ of the tropics are fairly strong fliers, carry 
through the air heavy loads of pollen and other material, and are 
a very successful group, judging by their numbers and their 
wide distribution, but their wing-venation is so reduced that 
only a few moderately well-developed cells remain. It would 
seem from this that the need of an elaborate network of veins to 
strengthen the wings of bees is not very great, if, indeed, there 
be such a need.” This seems to me an argument from an ex- 
ceptional case. 
The reduction of veins is associated with the importance 
of the veins as strengthening elements. In 2, 236, the reduction 
is stated to be associated with small size. 
Families of small bees. — The submarginal cells are reduced 
to two in Panurgidse, Dufoureidse, Macropididse, Prosopididae, 
Pasitidse and Megachilidae. The Megachilidae contain some 
middle-sized bees, but none equaling the largest of the 3-celled 
species. The typical forms are small, like Prochelo stoma, the 
larger ones being developed from these and retaining the same 
two cells. 
Obliteration or reduction to stumps tn anamalous cases. 
The second cubital cell. — This is usually the shortest and the 
transverse cubital veins 1 and 2 are so approximated that, on 
the presumption of strength, one of them can be dispensed with. 
Of 289 cases, one of these veins is obliterated in 286 while the 3d 
transverse cubital is obliterated in only 3. In Perdita obscurata 
the 2nd cubital cell is small and petiolate, indicating that in or- 
dinary Perditinse the two cells are the 1st and 3rd. In one spe- 
cimen of Pseudopanurgus compositarum transverse cubital vein 
