Since stick-on patches and slogans became popular, it seems to me that the quality has gone down (cheap imports cashing in on a trend, I guess). I'd use free-hand embroidery instead.
1. Start with what has caused the hole. I've never had moth damage in my life - are you sure it's not just natural weakening of the fabric (of so, you'll be mending the flipping thing for ever and a day)?
2. What is the jumper made of: wool, cashmere, acrylic, alpaca? Try to decide how precious it is to you before you invest a lot of time and expense in repairing it.
3.Where is the hole? Will it look odd having a patch there (in which case you'll probably never wear it happily). Of course, you could make more than one patch over the jumper, so it doesn't look "odd".
4. As long as the hole isn't too big I'd embroider a motif over it - for my money, patches are unreliable - the weight is never quite right and, again, can make the garment look odd.
5. Do the job properly! Darn the patch loosely first and tack a small square of thin cloth at the back to strengthen the flaw; then, if you have one, put an embroidery hoop over the area while you work (not so tight that it pulls the fabric out of whack). After it's done, trim back the excess fabric - not too much, just enough to stop it bunching or flapping.
6. Other ideas: If the hole is in a sleeve, could it become a short-sleeved jumper - or could you perhaps put a contrasting band around the whole arm?
6. Finally, ask yourself whether you really want all that work (if so, great, knock yourself out!) or can you buy a new jumper you'll love just as much and use the old one for something else (dusters, for example)?
