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Index of Subjects Thanks to all respondents for the info, and I think everybody is right on this one in some sense, where the colloquial name 'snowfleas' usually does refer to Collembola, springtails. I should have used 'snow mecopterans', Boreidae. The confusion was generated by my adoption of this casual terminology directly from a paper in 2006 by John Edwards of University of Washington in Seattle. He mentioned it in briefly describing some mecopterans he had encountered on snow in Europe, whose jumping prowess he found to be independent of temperature. This is what interested Malcolm Burrows, whose work recently has been aimed at uncovering the mechanisms behind the jumps and other rapid movements of various insects and crustaceans. The Edwards specimens are definitely Mecoptera, and the only genus found in eastern N. America is Boreus with 2 species (to see photo'd specimens, browse to BugGuide.net and type 'Boreus' in the search box -- you don't have to be a member). Briefly, none of these insects can make the jumps that they perform by instant application of muscle force (no muscle is that powerful or fast enough to accelerate the load sufficiently). Instead they have to use their muscle power to slowly wind up tension in some other structure, which stores this energy for quick release on a trigger, like a crossbow. It was thought that the storage structure was the almost perfect natural rubber 'resilin', in true fleas for instance. But what came out of the work we did when Burrows was here last was that this won't work either in the champion jumping bug we looked at -- resilin is simply not stiff enough, according to our engineer colleague Greg Sutton. It appears that the energy is stored by bending a composite internal material made up of insect cuticle (stiff enough) plus some resilin (shock absorber?) -- we compared this to Mongol composite archery bows that very effectively used a similar principle, as a horn-wood-sinew glued triplex in that case. It is likely that Malcolm Burrows will be here only up to early December. Has anyone encountered 'snow mecopterans' that early in the winter in N.S? Or, I wonder if you can find their immature stages? He needs a few live ones to photo their take-offs with an ultra-high speed camera (I think it's capable of 30,000 frames per second but he uses it only to ~8000 fps). This time resolution is needed to work out the initial acceleration accurately, to know what you need to explain for the particular insect. Steve Quoting Anne Mills <ocotillo@ns.sympatico.ca>: > When I was teaching Terrestrial Diversity in the Biology Department > at Dal., I always had a sample of the wingless insects on display in > the lab for the students. Andrew identified them correctly as > Collembola but I will add here that they are from one of 5 groups > (orders) of "wingless insects" (subclass Apterygota) that we studied. > The Collembola are the springtails or snowfleas that one sees on pond > surfaces or streams at this time of the year. I used to see them > often at the Hd. of St. Margaret's Bay up in the woods either on the > trail or at the edge of the stream running down the hill. They come > in various colours - black, rust, bright yellow and blue! although I > have not seen the latter two colours. If you find a largish cluster > of them on the snow put your ear to them and you'll hear little click > clicks as they jump. > > Anne Mills > > > ----- Original Message ----- From: "Joan Czapalay" <joancz@ns.sympatico.ca> > To: <naturens@chebucto.ns.ca> > Sent: Tuesday, February 16, 2010 6:45 PM > Subject: Re: [NatureNS] snow fleas (probably Boreus, Mecoptera) > > >> We used to see them a lot around the shady side of the school in >> Port La Tour, Shel. Co.. I had someone from DRN identify them as >> "snow fleas" for our outdoor nature class, but don't remember the >> scientific name. Seems we always saw them on an unusually mild day >> in Feb/early March. Cheers, Joan >> >> Stephen Shaw wrote: >>> Has anyone into winter hiking come across these, snow fleas (Mecoptera = >>> scorpionflies)? >>> They are expected to be black or brown, about 3 mm long, flightless >>> (vestigial >>> wings), come out on to the snow surface in the day in winter, and >>> can jump. They have been photo'd from early December through mid >>> February on >>> Bugguide.net, in places like New Hampshire and Ontario. The >>> species featured >>> on Bugguide are mostly Boreus brumalis and Boreus nivoriundus. >>> >>> A colleague from Cambridge, Malcolm Burrows, who visited here a >>> couple of years >>> ago to work on jumping mecahnisms in true bugs, is coming back >>> again later this >>> year. He is the expert on the mechanics of insect jumps and has >>> just asked me >>> if any species of Boreus is found here. Has anyone seen any >>> jumping critter >>> like this somewhere in N.S., and if so at what sort of date? >>> Thanks, >>> Steve >>> >>> >>> >>> >>> >> > > > -- Stephen R. Shaw Ph.D. Dept of Psychology & Neuroscience Dalhousie University 1355 Oxford Street Halifax, Nova Scotia, Canada B3H 4J1 e-mail: srshaw@dal.ca phone: 1-902-494-2886 fax: 1-902-494-6585
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