Eastern/Canadian Tiger Swallowtails

[Pavulaan at aol.com]

kirk.zufelt at utoronto.ca wrote:
>
> I am interested in opinions in regards to the validity of these insects as
> seperate species. Having lived in the so called "hybrid zone" for many
> years I am confused why all the specimens I have seen are "hybrids".  On
> examining numerous specimens from Southern Ontario I have seen no clear
> Eastern or Canadian Swallowtails they all appear some where in between.

Kirk:

I collected (here go those COLLECTORS again!) in New England and New York for
many years.  In Rhode Island, we definitely have both northern canadensis and
southern glaucus.  Canadensis, though rare there, has a single spring brood
in Rhode Island, where it is small and distinct from the (equally rare)
spring brood of glaucus.  These glaucus are virtually identical to the ones
from further south.  Both entities fly in May-June, while glaucus has an
August emergence (2nd brood).

I reared (oh, no, USDA is gonna get me) R.I. canadensis from egg on, and
could not get them to emerge the same year.  They are obligate diapausers.
 Though all of my pupae made it alive to the next spring (pupal movement),
they all dessicated before eclosing.  

I also reared R.I. glaucus (from spring female) and got emergers the same
year (summer), which emerged when the late summer brood appears in R.I.
 These were identical to the southern U.S. population.

However, I often wonder about the LARGE individuals that appear in June (in
R.I.), that look like canadensis but are as big as any summer individuals.
 These start to appear weeks after both small, typical, spring canadensis and
glaucus appear, and they are the typical "Tigers" seen in July, having a long
flight (probably long life-span of several weeks).  I used to think they were
a second brood but they fly too early to come from any of the early spring
ones.  And I never saw any canadensis as big as these guys.  To make matters
more interesting, they are also obligate diapausers.  I managed to overwinter
chrysalids, but only got a few to eclose!  Can these be the in-between ones
you referred to?  Perhaps they are hybrids, but the population breeds true.
 Interestingly, the females look very much like males, with minimal blue on
the upperside hindwing.  I even got one female that has male coloration (no
blue).

Hope this helps somewhat.
Harry Pavulaan