Saturday, June 04, 2011

Survival of the fittest...

It's a harsh place, the world of the insect. However, nature has come up with some remarkable ways of giving them a little 'edge' that may, just may be enough to protect them from at least some predators.

If an insect or bug can trick it's enemy into thinking that it's something less tasty, or more dangerous, it will often survive.

Take a look at the these images:

Can you be sure how many of these insects process a sting? Are these all bees or wasps? Or, are none of them?

Just as we are, birds too would be unsure and therefore tend to leave well alone. Mimicry at work.

(Answer to this picture will be at the end of this blog entry.)

In a similar vein there is a beetle that uses the same tactic of yellow and black stripes to try and deter birds etc. from attacking it. It's even called 'The Wasp Beetle'.

The Wasp Beetle (Harmless)

Most insects rely on concealment for safety. Many species will chose to hide away in dark places where they won't be seen.
This is especially true of the insects that are only active at night (another ploy to avoid detection by predators). Many of the butterflies will have beautifully marked and elaborate upper wings, but because at rest the wings are closed, they tend to be dull underneath so that once closed, they blend into the background.

 Peacock Butterfly (Upper wings)

Peacock Butterfly (Underwing)

In a similar way, butterfly and moth caterpillars also have a huge variety of 'cunning plans' (as Baldrick would say) to foil any would be threat.

Caterpillars are masters of disguise.
A twig?

A fallen twig or branch?

What about moths themselves? The day-flying moths are going to be in need of some form of protection and they often take on the same colouration as the trees you find them settled on.

Even the smallest of insects and bugs use camouflage as a means of concealment. There is a tiny hopper called 'Ledra aurita' that few people have ever seen. Not because it's all that rare, just because it likes to spend it's time on lichen-covered twigs and has evolved at shape and colour that is a near perfect match.
Ledra aurita (nymph)

Of course no matter how good the disguise, it's never fool proof. If it were, then I would not have found this example and been able to share the photo with you all.

Warning colouration:
The wasps and bees we've already talked about fall into this category. They have no need to hide.Birds will recognise the warning colours and leave them alone. The venomous sting is also enough to discourage most other predators  from launching an attack.

Warning colouration often consists of red and black markings as well. Just the sight of this combination of colours will be enough to save the insect from becoming another statistic at times.

Warning colours on a Plant Bug.

The same combination on a Frog-hopper.

A great many insects are protected from predation not by possessing a weapon or camouflage but by evil-smelling, ill-tasting or even poisonous body fluids.
Larva (caterpillars) will frequently feed on plants which have bitter or poisonous sap and will then retain some essence of this at all stages, hence any unsuspecting bird will find the thing foul tasting.

Coreus marginatus

Pictured above is a common Dock Bug. They are also referred to as 'Squash Bugs' though. The reason being, they emit a nasty smell if squashed. Another defence against attack.

There are so many other ways that insects have developed for survival. Little things like the humble greenfly or aphid rely on reproduction. They give birth to so many young that the fact that such a lot won't survive to adulthood doesn't effect the overall population too much.
Some find safety in numbers, others have a heightened sense of smell that alerts them to impending danger.

Then there are those that have huge eyes in relation to the rest of the insect or bug. King of these must be the dragonfly.
A dragonfly has a compound eye constructed of up to as many as 28,000 units.
Eyes of this kind produce less accurate pictures than human eyes, but are very efficient at detecting movement and it's been said that a dragonfly may be able startled by a sudden movement 40 feet away.

Dragonfly compound eyes.

Perhaps in a future blog entry I'll look at some other ways of insects and bugs being able to tip the survival scales a little in their direction, and also try and cover how evolution has equipped them with the tools they need.

Until the next time then....

Oh yes! You'll be wanting to know which picture, if any is of a wasp or bee in the collage? Well, actually there's just one. Middle photo, bottom row is a bee. The rest are harmless flies. But then you knew that?


  1. Yay, I got it right! :) You got some neat shots, but I think the dragonflies eyes are the coolest!

  2. Just trying out the comment thingy myself :
    Seems a bit 'long-winded' but I guess once you've done it once, it's O.K.

  3. Thanks for the comments on the dragonfly pictures :) One of my real favourite beasties!


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