Do our bugs hibernate?

[hawkmoon1704]

What happens to our little critters at this time of year? Which ones go to sleep and which ones brave out the winter in search of food?

How rare is the stag beetle? I saw some when I was a kid we collected them in jam jars from a rotten tree that had fallen but I've never seen em since.... did I make 'em extinct? (now that's one big beetle)

[Dogghound]

Yes most invertebrates hibernate, although some of them remain active for parts or all of the colder months. There are so many they all have different strategies for surviving the winter and different life phases that they hibernate as i.e. egg, pupa, adult or as nymphs or larva.

Stag beetles are uncommon and restricted to several sites/areas of old woodland mainly in the south of England, their range has declined but with good management and care in some places they are doing fine.

[Toby]

It was reported in the news recently that with warmer winters some species of Bumblebees have ceased to hibernate in southern UK and are now active all year round. Good time of the year to find Springtails if you have decent eyesight.

[Paul mabbott]

We probably ought to define what we mean by hibernation. Generally it's taken to mean a physiological response which depresses physiological activity over winter. As such all insects have depressed activity whenever the temperature falls so that their 'hibernation' is actually, generally, not a lot different from what they do on a cold day in summer!

Hibernation is, for some people, specifically for mammals and some other vertebrates - it involves behavioural processes (finding or building an over-wintering place) as well as physiological ones (hair growth, colour change sometimes, contraction of peripheral blood vessels, switching off of appetite, depression of brain activity in general etc etc).

As noted above, invertebrates have a much simpler response: their whole metabolism gradually slows down as the temperature declines (it's chemistry rather than behaviour or genetics) but there are some behavioural elements - they will often seek shelter as temperatures decline and will often aggregate. However 'hibernating' beetles (for instance) will commonly "wake up" if the temperature rises. Many beetles, of course, remain unaffected by other than the deepest mid-winter - larvae boring within trees are insulated as, indeed are beetles living in the soil - killing frosts do not penetrate deep enough in UK.

I've often been up on the moors, in frost or snow, in deep winter, turned over a rock and found ground beetles walking around .... I didn't awaken them from 'hibernation'. Polar bears would have been a different matter

[hawkmoon1704]

Thanks for your replys guys that make things much clearer.

[Hobjob]

V good reply from Paul.

Curiously bears (N American) don't hibernate in spite of popular belief, they don't drop their temperature enough and are easily roused - it is these days called "denning".

Defining things in nature and science gets more and more difficult as we learn more and more. It often seems that little of what I learnt at Uni in the 60s is true today

[3vilX]

There are too many different species to name individual seasonal patterns, but all insects are affected by it :P