JamieV. jamievande@freenet.de
Fri, 06 Oct 2006 00:50:49 PDT
J.E. Shields schrieb:
> So far as I can recall, female butterflies find the larval food plants on 
> which they lay their eggs by some combination of senses, including odor and 
> "taste" (if you call it "tasting" with their feet).
> While moths find nocturnal nectar sources mainly by odor, I think 
> butterflies locate their diurnal nectar sources mainly by sight -- again, 
> if I recall things from the past correctly.  I never was an entomologist, 
> but as a kid I had intended to become one.

Jim,  your memory is still good, but more has been learned in between.  
Most insects have excellent form and colour differentiation, which they 
use to identify food sources (which is why they easily spot whole fields 
of their favourite crops!)  As already mentioned, like birds, they see a 
much wider range of the spectrum as humans and are drawn to patterning 
in blossoms that we see as monochrome.  White blossoms may actually have 
strong patterns in the ultraviolet spectrum.  Interestingly, most red 
blossoms are avian pollinated, which would lead one to beleive insects 
cannot or do not associate this colour with food.  Red flowers are 
rarely scented, although the foliage may be in order tp protect it.

Scent is extremely important to butterflies and moths, both of which 
have quite elaborate antennae, especially the noctunal forms.  
Interestringly, birds have a very weak sense of smell, if any, and are 
drawn by colours and, of course, shapes.  It has been theorized that 
certain flowers show distinguishing patterns in the UV range, that 
communicate things such as ripeness, available nectar, etc.  Not yet 
proven to my knowledge.  As to a birds colour vision, it is known that, 
with their 4 optical receptors, they distinguish very elaborate patterns 
in plumage, that we are unable to see.  This explains why they can tell 
the male from the female visually, when we cannot.  Also, many birds, 
especially in the groups of the Trochilidae (Hummingbirds) and 
Nectarinidae (sun birds), have evolved along with their food plants and 
are very specific; swordbilled Hummingbirds with Heliconias and 
Brugmansia sanguinea, Sunbirds with Aloes.   Of course, most of us have 
heard of the moth with the 12" probiscis that Darwin predicted must 
exist in order to take advantage of the nectar found in the 12" tube of 
Angraecum sesquipedale (Orchidaceae).

I have found that mints (Mentha, Nepeta, etc), in particular, attract 
butterflies.  Stinging nettles are an important food source for 
caterpillars of many European species, much as the milkweed is in North 
America. Coneflowers are attractive to a degree, but, as they are not 
European natives, they may have a better reception in their native North 


Jamie V.

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