Cabbage Whites

[Michael Gochfeld]

Just about two months ago we were circulating emails among those of us
in the
East, lamenting the dearth of most butterflies and remarking on the
conspicuous absence of Cabbage Whites in particular.

Beginning about two weeks ago in New Jersey that changed dramatically.
Although most other butterflies are scarce to absent, Cabbage White's
emerged
with a vengeance.  I regularly count over 100 in a half acre yard, and
often
can see about that number from my window.  Other reports from northern
and
central NJ are similar.

It provides an opportunity to look at the nectar preferences, diurnal
cycles,
predation etc.  Today there were even two Cabbage Whites circling in a
heavy
rainstorm.

In our yard they are showing a strong preference for various mints 
(that's
partly because we have a lot of mints), but even compared with Liatris,
Buddlea, composites, and Lathyrus (Everlasting Pea)..

Catnip, Nepeta, Germander, Agastache, Oregano, and three species of
Mountain
Mints are the favorites.  Not surprisingly, being in the sun helps, but
there
is also a diurnal cycle.  First thing in the morning the Cabbages
congregate
on Catnip even in the shade.  The Mountain Mints don't attract quite so
early, even when they are in the sun.

There is another dimension---seasonality.  As the flowers age they
produce
less nectar and as they go to seed there are fewer florets producing
nectar
so the butterflies can exhaust them.  This seems to be happening to
Catnip
today, which is much less of a draw than it was five days ago.


PREDATORS
In some years I have counted over 100 predation events on butterflies. 
This
year things are starting slowly, but in the past week there have been:
1. Crab Spider eating female Cabbage on Buddlea
2. Ambush bug eating male Cabbage on Buddlea
3. Spider web with two trapped female Cabbage (spider not yet
identified)
As far as butterfly populations are concerned, these predation events on
adult butterflies are probably of little consequence compared with
predators
on early life stages including birds, rodents, and parsitoids.
Paula and Chris Williams have suggested that the tremendous increase in
Wild
Turkeys even in suburban areas of NJ, may have an adverse impact as
these
voracious consumers pick all manner of beings out of the litter.

Mike Gochfeld

 
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