1912] A Problem in the Flight of Insects 61 
CHANGE OF NAMES. 
Mr. C. P. Alexander has recently called my attention to the 
fact that some of the names that I used in describing certain 
Mipulacinemy article im Jour, NO Y.-Ent. Sec. Vol. [IX No. 3 
(1901), were preoccupied. Some of these I had noted before 
but had neglected to change them. I now wish to propose 
the following changes: 
Page 107, for Tipula clara substitute T. pellucida. 
Page 115, for Tipula concinna substitute T. olympia. 
Page 119, for Tipula albovittata substitute T. vittatapennis. 
Page 121, for Tipula contaminata substitute T. commiscibilis. 
Page 124, for Tipula graphica substitute T. fulvilineata. 
A PROBLEM IN THE FLIGHT OF INSECTS. 
HERBERT OSBORN. 
In the usual explanations for the flight of insects, the 
mechanism is considered essentially as a plane with a rigid 
anterior border, flexible hinder border and with a vertical 
movement so that the vibrations result in the forward propul- 
sion of the insect and, so far as I am aware, no further discussion 
of the modes of progression have been presented. There is, 
however, another feature in the flight of insects which appears 
to me to be well worthy of notice and which is not explained by 
the application of these principles, at least without some 
modification. Insects, aside from the direct forward flight, 
are able to hover or even fly distinctly backward as of course 
everybody who has observed insects must have noticed. It is 
only necessary to recall the hovering flight of swarms of insects 
in the air, such as midges, gnats, certain species of flies, May- 
flies, and even grasshoppers, to appreciate the distinctness of 
this feature of flight. For a distinctly backward progression, 
we may cite the approach and retreat of the hawk moths in 
their visits to flowers, the backward and forward movements 
of bees as they light or rest upon plants, the dragon-flies, and 
perhaps especially the backward flight of the honey bee in its 
initial flight from the hive when it is fixing the location of the 
entrance to its hive. 
Now if we consider the mechanism of the wing as simply a 
membrane with a rigid anterior border and the progression 
