Codling moth caterpillars in apples are a real nuisance: the young caterpillars tunnel straight into the developing tiny apple (known in old English language as a “codling”) and consume the growing fruit and seeds that form inside. 
It’s not nice to bite into one of those caterpillars! 
To keep the caterpillars out of your crop there are a few tricky things you can do. The first thing is to employ a codling moth pheromone trap. 
This often triangular contraption has a sticky base and a small rubber cap full of artificial pheromone, that leaks a good dose of sex-attractant for the local male population. 
The guys will get very excited about this smell and literally race towards the trap, while preparing for the mating sequence in mid-flight. Of course, it all ends in tears for the poor blokes as they may find themselves stuck with their Family Benefit on the sticky surface. 
The technical term for this is "mating disruption". 
But it also allows us to precisely time the peak mating flight period of the first generation – about now to late October! 
Approximately 10 days after peak flight the resulting eggs will hatch and it’s time to put a spray on your apple trees. 
Traditionally it was the organophosphates (maldison) and carbamates (carbaryl); these days (without those insecticides) it could be Yates Success or Btk (Bacillus thuringiensis var kurstaki - a bacterial gut disease of caterpillars). They’ll work to stop the caterpillars in their tracks, but they are not always 100 percent effective in preventing the caterpillar to start the tunnelling, still causing some damage and rots. 
These days there's a codling moth granulosis virus that will affect the small brutes before they enter the apple. The name of that virus-in-a-spray is MADEX 2. It is now available for home gardeners and not just for commercial growers. Have a look at your local garden centre or PGG Wrightson and Mitre 10 to see if they stock it. 
Last season I sprayed my apples with Madex from late-October until the end of February every two to three weeks and had no codling moth inside the hundreds of kilos of apples I harvested. Previous years – before using this technique - were an absolute disaster. 
Just be aware that crab apples and walnuts are also among the codling moths' favourite hosts so spray them as well with Madex 2. 
In the myth department: note that cardboard bands and grease traps around the apple trunk are an absolute waste of time. 
Just keep on monitoring those pheromone traps... and keep grinning! 
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