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ada?<div>cheers,=A0< Hi James, Thanks for the details, interesting. Following on from this, if you are going after Diptera too, as you probably know, there are a very large number of fly species out there, one guess putting them as second only to beetles worldwide. They are underwhelmingly known partly because both lepidopterans and hymenopterans have been preferred by collectors. Many of the life cycles are not known, or known only for one or few species in a family, and many live covert lives out of sight, underground, in stems, etc. I know the locale and flight period for a large empidid fly that I'm interested in, in the very large genus Rhamphomyia that needs revision (>100 species, some unnamed and undescribed). Fortunately, experts in the group were able to identify the species just from images, but the larval and pupal life histories aren't known. Why this note? It just occurred to me that another source you could try would be BugGuide.net, though the task would be much larger and even more tedious to analyze than for local butterflies*. Each image of a specimen is accompanied by the photographer's name, but also by a photo date and a location. You could get some idea of the flight time of the adults from the average date if there are a number of photos for a species, taken from a similar latitude (it's mostly adults). The 'advanced' brachyceran family Tachinidae is one of the largest and they pretty much exclusively parasitize other insects, often lepidopterans, and because the fly will emerge for someone who collected the moth caterpillar, the host is sometimes known: the recent example of a couple of tachinids that parasitize singing crickets, for instance. So you could infer the start of the larval period from the flight time of the adult fly in the photos. Tachinids might be a place to start. Sounds like a lot of grunt work sifting through, though -- more like a job for a summer student, for what's left of summer. Regards, Steve *:- http://novascotiabutterflies.ca/index.html ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Quoting James Churchill <jameslchurchill@gmail.com>: > Thanks for taking the time, Steve. Yes, a bit of a vague question, but > intentionally so. I am working on an article that involves comparing peaks > in abundance of different temperate zone diptera and lepidoptera > (caterpillars) with timing of bird breeding stages. > > Some literature suggests that, in general, there might be distinct peaks in > caterpillar abundance for forest-associated lepidoptera species > having deciduous vs coniferous host plants. And I am wondering whether > there are life history or ecological factors that would also lead to this > somewhat bimodal distribution of peak abundance ( if in fact it is a > documented phenomenon in North America). > > Thanks for the ideas and I will definitely check the site you mention. > > Cheers, > James > > On Friday, August 23, 2013, Steve Shaw wrote: > >> No idea, but it sounds like a bit of an odd question. Are you trying to >> tie it to bird abundance or migratory period, the timing of which might be >> more rigidly (and unfavorably) fixed for bird migration than for insect >> emergence if the climate warms up, as I recall some have speculated? >> >> As herbivors, you'd expect caterpillars to be dependent upon when their >> special food plant(s) starts to sprout, which is presumably variable for >> different species plus weather-dependent. For arboreal caterpillars, there >> are no (or few) leaves on deciduous trees around here (Halifax) until about >> the third week in May, but in Washington DC (etc) when we lived there, >> much further south, things started to warm up in March; same or earlier in >> Vancouver. As well, certain species have more than one generation per >> year. >> >> A way to check at least for butterflies in NS would be via the on-line >> nicely revamped Butterflies of NS site, which besides images gives the >> empirical flight period data actually observed for each species, but also >> the inferred egg-laying and larval timing. Though apparently not usually >> measured directly, the latter may be quite accurate because the flight >> period of the adult is usually quite short, so the eggs obviously have to >> be laid before the end of that. You'd have to go through it species by >> species and compile an average histogram by week, if that's what you're >> after. >> Don't know how you'd do it for the much larger number of moths, but Jim >> Edsall or others might have some sources. >> Steve (Halifax) >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> >> On 23-Aug-13, at 3:42 PM, James Churchill wrote: >> >> or roughly June and August for Canada? >> cheers, >> James. >> >> On Fri, Aug 23, 2013 at 3:25 PM, James Churchill < >> jameslchurchill@gmail.com> wrote: >> >>> hi folks, >>> >>> Can anyone provide information on the temporal distribution of >>> caterpillar abundance in NS or North America? >>> >>> Do we by chance have two peak periods of caterpillar abundance >>> corresponding roughly to May and September? >>> >>> cheers, >>> James. >>> >> >> -- >> James Churchill >> Kentville, Nova Scotia >> jameslchurchill@gmail.com >> (902) 681-2374
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