You've heard me say it before, and I never get tired of saying it - a pond is one of the best and most exciting things you can do for wildlife (and just as much for you) in the garden.

Mine are constant sources of delight, enough that two more are going in this autumn to add to the five I already have (call it greed? I call it a thirst for ponds!).

So, this week I was merrily enjoying the Ruddy Darters that appear to have colonised my main pond:

What absolute gems they are. They are one of our small autumn dragonflies (quick reminder: dragonflies = wings held out flat like an aeroplane; damselflies = wings held behind their backs closed together or occasionally half open). Male Ruddy Darters like this one are paint-tube blood red with a distinctly 'pinched waist' effect along their abdomen.

Much commoner over my pond are the Common Darter (below), in which males have only a hint of pinchedness in their slightly orangier abdomen. The differences can be subtle, so it's a case of really concentrating!

Common and Ruddy Darters are worth creeping up on from the side (and they will allow you to do that if you're careful; it's a good test of your guile), because Common Darters have yellowy patches on the side of their thorax (below), which Ruddy Darters don't.

I then also spotted a Migrant Hawker, a rather larger dragonfly.

This is a female, with pairs of small yellow spots down a largely brown abdomen. I more usually see these circling high up around the outer edges of trees, sometimes several together seeming to tolerate each other's presence, whereas most large dragonflies in the UK would quickly have a spat, full of the crackle of papery wings clashing.

But then I spotted something rather blue, and I am partial to a bit of blue, whether it be flower or creature.

It is a Blue-eyed Hawker, or in some books it is called the Southern Migrant Hawker (which is a tad confusing given that there is a Southern Hawker and a Migrant Hawker already).

Apart from one record in the UK in 1952, it wasn't then seen again until 2006 when four were seen, and here in Sussex the next didn't appear until 2015.

Now there are small breeding populations along a number of the large rivers in my county, and it has been seen along the English south coast and as far north as Lancashire and Yorkshire and west to Cornwall.

You can see how it gets its name. The thin black stripes on the sides of the thorax are also diagnostic.

It appears that my record is currently the latest in the calendar year yet recorded in Sussex, although I'm sure that will soon get beaten.

Once again, isn't it amazing what will turn up in gardens if you provide the habitats for them?

And isn't it astonishing how the geographical ranges of wildlife are changing right in front of our eyes. Insects are such a fine-tuned barometer of our climate and here is another piece of living evidence that climate change is not a thing of the future - it's happening right here, right now.

So I found myself gazing into those blue eyes, lost in their beauty, but with that strange sense of alarm bells ringing at the same time!