How do butterflies flit?

[Richard Worth]

Hi Richard,

Dump that book if you still have it and get a butterfly biology book.  Kidding.
Butterflies and moths have evolved tiny, deciduous scales, actually 
believed to be modified hairs, to cover the wing surface.  These are 
your "feathers" and also the "butterfly dust" you may have got on 
your fingers from handling them as a kid.  They do not really control 
the flight patterns, since there are no muscle attachments to these 
scales.  But they do have many significant purposes.  One of course 
is the colors and patterns they create, either to hide from or 
frighten enemies, warning coloration to advertise "bad taste" to a 
predator, or for mate recognition.  They also are like shingles on a 
roof and allow water to roll off.  Another use for protection against 
predators is by sluffing (sloughing ?) off scales if attacked.  It 
not only helps them escape because they are slippery, but scales can 
cause serious irritation to the esophagus, trachea, eyes, and other 
mucous membranes.  I have also heard that some people have allergic 
reactions to them as well.  The scales lay flat and may help reduce 
wind drag over the wing surface, though.

Most moths don't seem to flit much, though some do.  Most have more 
of a constant wing beat and some even hum or buzz and look like 
bumblebees or hummingbirds.  Butterflies are more known for the 
"flitting" action.  The pattern of the flitting can actually be 
characteristic of certain groups, or even species, of butterflies. 
It is genetically hardwired.  The insects actually control their 
flight by changing the angle of attack of the leading edge of the 
forewing to the air and also steering with the hindwings.  Slow 
motion photography shows this very well.  It actually looks like a 
wave motion with the forewing rolling down and forward first and then 
up and back.  If you pay close attention to the butterfly flight 
patterns you will start to see the differences.  Satyrids have the 
most bouncing, bobbing flight and are generally slow; nymphalids 
often have a powerful, erratic flight when startled but can have a 
repeated "flit-flit-glide" pattern when patrolling; Colias sulphurs 
often have a fast, close to the ground zig-zaging flight;  skippers 
get their name from their flight;  swallowtails have a classic 
fluttering---actually there may not be a more beautiful sight on the 
planet than one of the giant, irridescent birdwing species from New 
Guinea or the Solomon Is. in slow, hovering flight.---And Monarchs 
are the pros at taking a few flaps and gliding like the best hang 
gliders in the world.
So that's "Scales and Flight 101" in a nutshell.  It's more complex 
than this but that's volumes of literature.
Cheers,  Rich

>I read a book when I was a child about how moths and butterflies can
>flit.  From memory they have tiny "feathers" on their wings which act as
>
>"flaps" and by controlling them they can dramatically change their drag
>on the top or either side which allows them to flit.
>
>Are my recollections correct - or even close?
>
>If not -  how do they flit.
>
>Richard Grace
>
>
>
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Richard A. Worth
Oregon Department of Agriculture
Plant Division
rworth at oda.state.or.us
(503) 986-6461

 
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