The Undesigned Chapter, pt VIII / "The class of 250+ million years"

”Just as the Paleozoic is often called the age of the trilobite, modern time is often called the age of the insect.” 

- From the Wikiped. article Phylogeny of the insect 

    (from Paleozoic, See)

...Of the (multitudes from) insect genera and species having existed during their ”early evolutionary path, past the millions and millions years”, not very comprehensive view seems possible acquire. Quite understandable, because the insects appear small, often tiny animals, that lack any skeletal parts which would fossilize (Instead, they have so-called exoskeleton). Also, the insects do 'regenerate' quite rapidly - for they are short-lived, and a short period of time can often produce many successive generations. As result (from that and other related aspects) – any view from their evolutionary past seems always been (very) fragmented and incomplete some.

 

However, of that past evolution a brief general 'walk-through' can be presented (at least I try, on basis of what I've been able to gather from some general books dating almost couple decades old now. Naturally, you can easily seek much newer information about it, too. I only picked a few interesting topics for the purposes of this...) 

 

Seems – or, at least was formerly believed – that of the still extant insect genera most archaic forms contain (at least) the Ephemeroptera (ie Mayflies), Blattodea (ie Cockroaches ; how surprising...) and Orthoptera (Grasshoppers, crickets and katytids). All these are believed have existed (in their earliest origins) already closely some 300 M. year ago (on the Carboniferous-age, or perhaps even since from Devonian period). Most archaic forms were of course lot different compared to their modern ”descendants”...but sometimes them are also believed (relative) little changed of their early origin. (So, fx also the Odonata (Dragonflies) are believed very ancient by origin and did exist already during the Carboniferous. Already then they did fly and the group contained some from largest and earliest flying insects known from; Yet, their modern forms - similar or resembling to current species - seem believed having evolved 'only' during the Late Triassic, about 200 M. y. ago) Of the other rather old groups seems it believed that the Plecoptera ('earliest' Antlions, Lacewings, etc....However, seems that the correct class or 'group' from these would be Neuroptera...but the Plecoptera are also believed rather ancient...), Hemiptera (the 'true' Bugs, whatever that exactly means...), and - the Coleoptera (Beetles) – did evolve approx. some 250 Million y. in the past. Also, Mecoptera (Scorpion flies, etc.) may have existed at least around +200 M. y. ago ; And, interestingly, I saw someplace said that the more modern insect genera – fx the Flies and earliest Butterflies/Moths - might have evolved from some (unknown) separate/co-existent lineage of that group, by origin. 

 

...However, some of these dates maybe are 're-evaluated' by now since there's probably lot more recent studies that what I've viewed. Also, there's of course lots insect groups that one would suppose having existed long ago in the past, but which are 'lot less exiting' from features (fx, the Bristletails - so called Arghaeognatha - are some wingless insects that seem believed represent some from the very oldest species/order). And one could easily suppose that there's possibly not any clues been preserved (fossilized) of many genera because they appear so small tiny creatures (fx some species comparable in sizes to the 'modern' termites and fleas).

So, the insect evolution obviously is some particularly fragmentary and scattered puzzle. Yet, there's also one aspect which seems serve as functional way for to dividing between their old and more ”modern" genera. That is, if the insect species have only partial metamorphosis- or, more correctly it's the gradual metamorphosis (so called Hemimetabolism). Alternatively, them might have the complete metamorphosis (ie Holometabolism). The first category (partial/gradual) contains (fx) Mayflies, Cochroaches, Grasshoppers (...etc.), Dragonflies, the Bugs (Hemiptera) and Lacewings(...apparently?). However, the Beetles and Mecoptera (+ anything later evolved) usually seems represent the complete Metamorphosis. ...And likewise most other from 'modern insects', but this dividing is not considered too universal anymore; For example, there's the Thrips (Thysanoptera) some tiny small insects that are said to represent quite different manner from metamorphose which comptetely doesn't resemble either of the above described. (Seems said them (Thrips) are yet believed rather old group, and also appear pollination agents of some plants (on tropics and the Nothern latitudes, although that's apparently about the same procentual amount from all than the birds, ie smtg less than 0,5 per cent...by supposed, estimated figure).

(...This is (possibly) some common species of the Ground beetles (Carabacidae). (Dead, but...) of the pic a typical Coleopteran structure is quite observable. Shows fx the Elytron (hard, scelerotized cover-wings), which all/most Beetles have as their protection.)

 (...To the right,  Bee beetle (Triachus fasc.), on flower at garden fence. Like one can see it nicely mimics the bumble-bee, at first I considered it a bee...)

The Beetles (it is interesting to notice) we find also believed for some good candidates as the original pollinators for some earliest flowering plants.  ...But, it is believed) the Hymenoptera (Bees) maybe instead finally emerged as the more 'common-place' representatives on the pollination process. That so (seems it said) possibly due because the Beetles contain a lot of ferocious plant pests (ie leaf-eating species). Whichever the reasons/how evolution might actually have selected at that on the distant past, is at least noticeable there being about 200, 000 plants pollinated by the Coleopterans (means: 80 per cent of all...!). And, in comparison only about 1/6 - from all plants - is pollinated by the Hymenoptera (although many of those appear major crops). But these are probably rather general figures (from that Nabhan - Buchmann book, 1990s) – ie their estimates…At the moment I don't recall/have not any precise idea from how this is been counted (...more to the point; it's of course very difficult to estimate from any 'exact numbers', for many plants are pollinated by more than some singular species, some are (also) pollinated via the wind, and there's some pollinated by insects only on 'unfavorable/favorable' circumstances ie the insects sometimes serve only as the secondary method to pollination at some particular plants...etc.). Seems (to me) it fx likely that many of the Coleopteran pollinators may be species that specialize on certain plants, while there's more general pollinators on hymenopteran. Also, the coleopteran are most numerous on tropics, so feels likely that most of those pollinated plants (in question) also appear tropical by range...or, so I just guess on this basis...

 

(...This, on the right, is some from commonest Cerambycidae-species (ie the Long horn beetles). Looks rather fond of  Meadowsweet - like the beetles often are, I've noticed...)

(..This below also belongs for the Cerambycidae, I guess it's the Musk beetle (Arom. Muschata). Quite common, but seems it only appears sparsely on Fennoscandian Nature; More usual at the warmer latitudes. On fennoscandia it mainly increases on Willow.)

Among insects the Fennoscandian Coleoptera are quite much studied, in comparison for the most insects in the World. Yet, also there's lot that are not so well known. Fx, there's only a few species of Blister beetles (Meloidae) that do appear on N. Europes. Of those, at least half (two species) were found disappeared around early/mid of the last century, but seems that no actual reasons for that were to be found. ...I didn't bother check if they nowadays have any better idea about it (or if some species from those have been rediscovered), but that's actually quite typical for the insect-human relations. Often when we happen notice them, the species might be gone already (like usually is remarked from the lot more numerous species appearing on the tropical regions).

From some insect species the populations may also vary lot between years by natural reasons. For that reason, it is also often not too well known from how many of the species tolerate human-made change. (Yet, fx renownly much of the Cerambycidae don't well adapt to economic forest uses on Northern boreal forests. From the Finlands species, fx majority of the currently extant species are some adapted for the younger forests - ie some that age under 100 years.) 

 Finally to mention, this (brief introduction) only represented to provide some text along the pics from these few Fennoscandian Beetles. They're all of course usual and common species - In fact, due the relative recent time has passed since the latest ice-ages, not any insect species appear endemic solely to the Fennoscandian range. Most also appear at more southern ranges (But there's some very distinct, especial sub-species/genera.) 

...So, on the light of these views, I provided at begins of this also pic from that magician – it's Merlin. What Merlin really says is my actual view-point; What's mutual to the insect and humans at these ”manmade dead-ends”. For the dead-ends those are, solely if thinking about the distant, magnifient past evolution of the insects (Which I shortly tried to outline on paragraphs above.) ; (G.U.J.)

(...likely the Green Rose Chafer (Cetaria auralia), also found from the Meadowsweet at mid-summer. ...For some speciality, it's said that they have a small openings on sides, permitting them fly cover wings closed - unlike most other Coleopteran...)