Chuck wrote: Sat Mar 08, 2025 2:21 am JHyatt IIRC Adam said in the Marcellus thread that any flight can become any of the three flights the following year. Where cecropia has two flights it is the same situation.
L

Thanks, Chuck. I either missed that marcellus thread, or had forgotten seeing it.

jh

A splending species.
I still remember seeing it flying in Tokyo when I was 10 years old.

Release of the hormone that initiates diapause is triggered by daylength during late 4th instar and 5th instar larval stages. Generally, less than 14 hours daylength is supposed to trigger diapause in many butterflies that diapause as pupae.

Adam.

I reared glaucus here in the UK for a few years many years ago, which I reeared on Ash, although I don't know which form they were. I always got a spring brood which produced a summer brood in August. A small number of these went into diapause which produced the following year's spring brood, but about 80% of them emerged and produced eggs which were only half grown larvae by the time there were no leaves left in October.

On the subject of daylength, we have a species Polygonia c-album which has a summer form called f. hutchinsoni which produces a second generation and looks quite different from the typical form which will hibernate as an adult. I once collected some larvae from a f. hutchinsoni and reared them indoors under a long daylength, these produced further f. hutchinsoni individuals in September. I think this proves that in this species at least, daylenth is the only factor affecting diapause. Maybe your C. interrogationis behaves the same.

jhyatt wrote: Fri Mar 07, 2025 8:53 pm Are the late season specimens a genetic dead end, or do their ova overwinter?

I very much doubt that the ova will overwinter. They will hatch and either go through to produce small size pupae or die as larvae.

Adam.

Dave,

I am glad you like them. You did a superb spreading job on them.

Interestingly I could not breed any summer form specimens here. All pupae went into diapause regardless of the time of year, presumably because the day length here is less than 14 hours (11-13 hours depending on season) triggering diapause. This must be the reason that P. xuthus does not reach tropical zones. It gets as far south as northernmost Vietnam (Hagiang only). This species also has no subspecies, despite its wide range.

Adam.

livingplanet3 wrote: Sat Mar 08, 2025 2:47 am It appears to be a species of twig spider (genus Poltys) -

https://www.inaturalist.org/taxa/209672-Poltys

Thank you!

It appears to be a species of twig spider (genus Poltys) -

https://www.inaturalist.org/taxa/209672-Poltys

Could you help out ?

JHyatt IIRC Adam said in the Marcellus thread that any flight can become any of the three flights the following year. Where cecropia has two flights it is the same situation.

Late flying individuals of most any species that overwinters as pupae have a loss of survival. The late August and early September P solstitius lay eggs that cannot possibly reach the pupation stage. Bad luck.

Even those females that eclose August 1st- and it’s a high number- what of their offspring? And sometimes we have a mass emergence of Tigers (I presume solstitius) in mid August. What of their offspring? They’re all pupating at the end of September, when the trees are well turning and likely not very nutritious. Makes no sense.

Thank you!

Chuck wrote: Fri Mar 07, 2025 8:10 pm

eurytides wrote: Fri Mar 07, 2025 7:24 pm ow can it be that pupae from the summer generation know that short days means they should diapause but pupae from the spring generation don’t? They don’t have a calendar. All they have is physiology,

To be heretical, I'd say- they don't have a clock but know enough that the spring flight looks more like canadensis, and the summer flight doesn't. So what's the difference between that and whatever physiological element that controls dipause? Further, that it has been demonstrated that in some cases dipause is linked to daylight hours, but it hasn't been demonstrated in all cases (you'll never prove ALL cases).

eurytides wrote: Fri Mar 07, 2025 7:24 pm If glaucus in the north were always bivoltine, how can it be that pupae from the summer generation know that short days means they should diapause but pupae from the spring generation don’t?

Without much arguing "north", isn't that what glaucus does (virtually?) everywhere? Summer generation knows it needs to dipause, spring generation doesn't dipause.

In the "far north" if glaucus is univoltine, somehow it knows to be so.

In the "far north" if there is one generation of glaucus, first I'd segue and ask well is that the Spring Form or the summer flight?

If it's Spring Form in NY, it sure does have enough time for a second generation; where is it? And yet, in nearby Toronto area, there is no Spring Form, just the summer flight. Kinda odd that if both are glaucus, and both univoltine, one emerges in Spring and one emerges in Summer (though not unpresedented, Anax junius does it.)

The spring flight looks like canadensis and the summer flight doesn't. But this isn't because the insects "know" or make a conscious decision. The reason they look different is because one came out of a pupa after 10-14 days while the other stayed in a pupa and was exposed to cold temperatures for several months. It's a well known phenomenon that temperature exposure for diapausing pupae can alter their phenotype. Think about the shocked pupae that produce "fletcheri."

I'm not saying in the far north there is ONLY one generation. I'm saying that it's on the cusp of 1 vs 2 generations, so both might occur. Some eggs are laid earlier or develop faster due to genetic variation and can squeeze in two broods. Others cannot, and just have 1 brood. You are right, I have no idea if this is the same spring from you are seeing in your neck of the woods. But recall that Julian/Chris did genetic work on tigers from Essex Co. in Ontario and they came out glaucus (and different from MST and canadensis). It's possible that these are actually something else but just so close to glaucus genetically that they can't be teased out with the particular genetic tools that were used.

I have no experience collecting in Toronto, but in Hamilton which is about an our west and just south, we have glaucus that comes out in May and June and a second brood of tigers that can be seen in August. I have caught wild fresh specimens from August as well as raised them on tuliptree (from eggs in the spring that lead to a second generation the same year). Having said that, the August specimens are not numerous. So, I think that's why Chris suggested that they can occasionally fit two broods in, but a fair number of the tigers that emerge in spring just diapause and come out next spring. The ones that fly in August, I've never raised them so I have no idea if they are a genetic dead end or if their progeny have time to finish eating and pupate. It could be the case that they just always occur in steady-state small numbers due to selection pressure.

A bred pair of the spring form. Thanks to Adam Cotton for doing such a good job with these.

This discussion bringns to mind E. marcellus. Here in the southern Appalachians it is triple brooded: A short tailed spring brood, a longer-tailed summer brood, and a scarce, very long tailed and darker late summer/fall brood. Are the late season specimens a genetic dead end, or do their ova overwinter? If so, which form (or forms) result from these eggs? And do some of the spring variety's offspring emerge the next spring, and some the next summer or fall, looking quite different from their parents? Do the summer ones' offspring emerge as spring, summer, fall (or both, or all 3), varieties? Has this situation been studied? I've always wondered..

jh

eurytides wrote: Fri Mar 07, 2025 7:24 pm ow can it be that pupae from the summer generation know that short days means they should diapause but pupae from the spring generation don’t? They don’t have a calendar. All they have is physiology,

To be heretical, I'd say- they don't have a clock but know enough that the spring flight looks more like canadensis, and the summer flight doesn't. So what's the difference between that and whatever physiological element that controls dipause? Further, that it has been demonstrated that in some cases dipause is linked to daylight hours, but it hasn't been demonstrated in all cases (you'll never prove ALL cases).

eurytides wrote: Fri Mar 07, 2025 7:24 pm If glaucus in the north were always bivoltine, how can it be that pupae from the summer generation know that short days means they should diapause but pupae from the spring generation don’t?

Without much arguing "north", isn't that what glaucus does (virtually?) everywhere? Summer generation knows it needs to dipause, spring generation doesn't dipause.

In the "far north" if glaucus is univoltine, somehow it knows to be so.

In the "far north" if there is one generation of glaucus, first I'd segue and ask well is that the Spring Form or the summer flight?

If it's Spring Form in NY, it sure does have enough time for a second generation; where is it? And yet, in nearby Toronto area, there is no Spring Form, just the summer flight. Kinda odd that if both are glaucus, and both univoltine, one emerges in Spring and one emerges in Summer (though not unpresedented, Anax junius does it.)

So for example, let’s say you have a bunch of glaucus eggs laid between June 1 and June 30 and they take 6 weeks to finish the larval stage. Eggs laid early will be pupating middle of July, and they might get enough day light to decide to develop into a second generation.

Eggs laid later from that same flight, they will be pupating middle of August. If they develop into adults, that’s a genetic dead end because none of their offspring will have enough time to finish growing and pupating. Indeed, that’s probably the case sometimes. But some of those larvae will probably experience short enough days that they will diapause rather in develop into adults. I.e. they not are obligated to be bivoltine. The pupae from the eggs laid by tigers in this single flight is just as the cusp of 1 vs 2 generations and some will only have enough time for one generation before experiencing the environmental triggers that steer them toward diapause.

For obligate univoltine organisms, they diapause no matter what and only develop into adults after exposure to cold as pupae.

For organisms with facultative voltinism (which glaucus is, and I don’t think this is disputed), whether a pupa hibernates or develops directly into an adult depends on daylight experienced as late instar larvae. At the northern range limit of glaucus, some larvae will experience enough daylight hours to trigger diapause and some will not. That seems logical to me. I think past claims that all glaucus had to be at least bivoltine was due to lack of careful study. If glaucus in the north were always bivoltine, how can it be that pupae from the summer generation know that short days means they should diapause but pupae from the spring generation don’t? They don’t have a calendar. All they have is physiology, and that physiologic response to day length should be the same no matter what generation the individual is from. So if a summer generation pupa can be triggered to diapause, so can a spring generation pupa (i.e. univoltine).

adamcotton wrote: Fri Mar 07, 2025 6:46 pm
I am not sure which 'authorities' you are talking about since you didn't say, but perhaps P. glaucus is univoltine in northern areas and bi- or multivoltine in the south.

Adam.

That's been the long-claimed situation. And one expert says that is indeed the case, and one says no, no glaucus are univoltine (e.g., if it's univoltine it's not glaucus.)

Chuck wrote: Fri Mar 07, 2025 4:42 pm There is another issue: I have two authorities, one says glaucus is NOT univoltine, and another that says it is. Both refer to published research. Interesting, and highly significant which is correct.

I am not sure which 'authorities' you are talking about since you didn't say, but perhaps P. glaucus is univoltine in northern areas and bi- or multivoltine in the south.

Adam.

JVCalhoun wrote: Thu Mar 06, 2025 7:01 pm These taxa likely diverged relatively recently and are still in the process of speciation,

What I'm trying to wrap my head around is that 200,000+ years of "relatively recently." During that period (ice ages, specifically) these taxa (and I'll defer to only canadensis and glaucus to keep it simple) during which they were repeated pushed south, then crawled back north. I'd think the hybridization would have been very high. And, perhaps reflecting on bjorkae, solstitius and others, that's why we have potentially so many different taxa in microclimates.

I'd like to know any hearsay, conjecture, or published data on the topic.

There is another issue: I have two authorities, one says glaucus is NOT univoltine, and another that says it is. Both refer to published research. Interesting, and highly significant which is correct.