9 July 2025 UPDATED at 3:20pm
Tiger swallowtails are one of many few butterflies I can determine so I’m all the time joyful to see them within the metropolis parks. I assumed they have been simply plain “tiger swallowtails” till I discovered there usually are not simply two species (as I first wrote) however three in Pennsylvania. My thimble stuffed with butterfly information overflowed so I’m passing it alongside.
The jap tiger swallowtail (Papilio glaucus) is the one species we have now in Allegheny County as a result of the Canadian tiger swallowtail (Papilio canadensis) requires a cooler local weather.
In Pennsylvania P. canadensis is proscribed to the higher elevations so that you’ll discover them an hour east of us within the Laurel Highlands. Nonetheless, P. glaucus might be there too and the place their ranges overlap they produce hybrids. The Appalachian tiger swallowtail (Papilio appalachiensis), the third species in PA, was initially a hybrid of these two discovered within the Appalachian Mountains.(*)
Evaluate the Canadian tiger swallowtail (Papilio canadensis) beneath to the jap tiger swallowtail (Papilio glaucus) at prime.
The colours within the images might confused you however they hardly matter. Bugguide.internet for Papilio canadensis explains learn how to inform them aside:
Grownup: internal margin of P. canadensis hindwing has extensive black stripe (whereas the in any other case related – although bigger – Jap Tiger Swallowtail has a skinny black stripe in that space).
Larva: mature larvae os P. canadensis are darkish inexperienced, with two spots that seem like eyes on the swollen part of the physique behind the pinnacle; this creates a snake-like profile. Immature larvae are brown and white, resembling chicken droppings (CBIF)
You’ll be able to see the hindwing distinction on this side-by-side comparability in case you look intently. This ID tip depends on the butterfly holding nonetheless, eh? If it’s arduous to see within the images, click on on the picture for a marked up copy outlining it.
Their larvae have barely completely different meals preferences might assist determine them (listed beneath from Wikipedia).
Host vegetation of P. glaucus embrace:
Wild black cherry (Prunus serotina)
Ash (Fraxinus species)
Cottonwood (Populus species)
Wafer ash or hoptree (Ptelea trifoliata)
Frequent lilac (Syringa vulgaris)
Candy bay magnolia (Magnolia virginiana)
Tulip poplar or tulip tree (Liriodendron tulipifera)
Willow (Salix species)Host vegetation of P. canadensis embrace:
Birches (Betula sp)
Poplars, aspens, and cottonwoods (Populus sp)
Apple timber (Malus sp.)
Black cherry (Prunus serotina)The tiger swallowtails’ vary overlap and hybridization in Pennsylvania are just like our chickadee species overlap. See Pittsburgh’s Puzzling Chickadees for the story.
(*) UPDATE on 7/9 at 3:20pm: I initially stated two species however Bob Machesney pointed on the market are three. See his remark concerning the Appalachian tiger swallowtail (Papilio appalachiensis).
