If you're of a certain vintage - probably over the age of around 35 - you'll remember the dawn raids. No, I'm not talking about wartime air assaults or a policeman breaking down your front door. I'm talking about a much smaller, much quieter invader.

You can probably remember opening your front door to collect the milk bottles from your doorstep (yes, kids, milk used to arrive in something called a "milk bottle" delivered by someone called a "milkman"), only to find a big hole gouged out of the bottle top. Not only that, the cream was missing (yes, kids, milk used to contain something called "cream" and was covered with a piece of foil called a "bottle top". The latter was a special currency used by Blue Peter to buy guide dogs, as far as I recall).

The cream thieves were an intrepid and rather ingenious bunch. They crept up on milk bottles and, quick as a flash, pierced the foil top and devoured what my mother always referred to as the "best part of the milk".

What's more, their actions inspired others to follow suit. Up and down the country, the sound of a front door opening in the morning was generally accompanied by a loud tutting noise as the Great British Public realised that they had once again fallen victim to this cheeky gang of  thieves.

 I'm talking, of course, about the blue tit. No-one really knows when or where the first ingenious blue tit worked out that a milk bottle provided an easy, tasty breakfast. What's clear though, is that other blue tits, and the occasional great tit, were watching with interest and quickly learned to copy their pioneering relatives. Perhaps this was an early form of Twitter?

I still get my milk delivered (in bottles), but I suspect I am one of a tiny minority. Alas, the advent of cardboard milk cartons and plastic bottles, coupled with the demise of doorstep deliveries, put paid to the exploits of these avian cream rustlers. But the blue tit has never stopped being an opportunistic feeder with an experimental approach to mealtimes. And now it is putting these characteristics to good use.

If I may be permitted to share another childhood memory, it's of autumn lunchtimes in the school playground, locked in combat with my peers in a ruthless game of conkers. But, like the doorstep milk delivery, this staple of childhood is under threat. Not only from video games and health and safety zealots - the conker itself is at risk from the invasion of the leaf miner moth.

The caterpillars of this non-native moth were first spotted in the UK in leafy Wimbledon in July 2002 (perhaps they came to watch the tennis?). As their name suggests, they "mine" into the leaves of horse chestnut trees. The mines cause the leaves to dry out, go brown and fall prematurely. In extreme cases, a tree can die.

But help may be at hand from opportunistic blue tits. The sudden influx of leaf miner caterpillars has not gone unnoticed by these feathered fans of exotic cuisine. The Sunday Times reports that  Darren Evans, a biologist from the University of Hull, has found that blue tits have started to hoover up these invasive pests, which provide abundant and easy pickings during the breeding season.

As a child, I was never very enamoured of the idea of sharing my breakfast time milk with a pilfering blue tit. But I would have been much more forgiving had I known that the same opportunistic instincts could, one day, provide a lifeline for a much-loved tree and my favourite knuckle-bruising game.

photo credit: Ray Kennedy (rspb-images.com)

  • I'm well under 25 and have grown up with milk bottles delivered to the family home. After being told about these morning raiders as a child I spent years hopeful that we would have our milk stolen. It never happened though.

    During a recent visit to Notre Dame I noticed all of the horse chestnut trees around the cathedral had brown leaves and were looking decidedly autumnal despite it being July. It great to hear that blue tits might be creating a natural solution to this disease, and see nature in action, turning negatives into positives.