Every night Possum X would sit at the top of the lemon tree outside my bedroom and growl with the largest, deepest pair of possum lungs on the Southern Tablelands. More junior possums who'd mistakenly thought they might set up home would depart with a few half-hearted grunts. Possum X would then retire to his nest in the loquat tree, having munched his fill of young loquat leaves, blossom or fruit, according to the season, as well as quite a lot of juvenile blue gum leaves kept coppiced low for his delight, and just a few rose buds or oranges for a change in diet.

The we had the loquat tree cut down.

It was my fault. The 'loquat tree' was actually three planted close together, looking like one tree. I asked the tree loppers to cut down the one I thought was uninhabited. Possum X survived the fall, crawled out, gave a dance of rage, and scurried up the pergola into the roof cavity above our living room.

Since then it has been war. I think. Can war be raged only on one side?

Possum X now ignores the remaining loquats, and the gum leaves. He carefully sniffs each night to see what the humans have paid attention to, and eats that - the corn crop, the tomatoes, the lemons, eight apple trees kept almost totally defoliated, though he left the Jonathons so the fruit would mature. Possum X loves Jonathon apples.

As a house guest he's quite pleasant. There are many layers of wood and insulation between the roof cavity and the living room ceiling, so his ablutions don't bother us. He's not so fond of us, especially if we have guests in the afternoon when he's trying to sleep. Young guests who laugh loudly as we practice the 'chicken dance' are especially unwelcome. He growls, he shrieks, and if you still pay no attention, stomps out onto the roof, slides down the roof onto the upstairs patio, then exits via the pergola.

We could probably evict him - wait till he's decamped then block up his entrance, or put a ringed possum collar onto the pergolas to stop him climbing up. He'd probably find other ways to get in, but given the amount of noise he makes exiting, a week or two of observation would probably be enough to foil him.

There are two ways to get rid of possums in your roof. The first is to kill them, which includes trapping them and removing them. Most possum-friendly land is already occupied with possums, who will attack your possum, and your possum will probably die trying vainly to return to their own territory.

The other way is to be inhospitable. Years ago I recommended hiring a mobile disco with strobe lights. Two days of this works most effectively - the combination of noise and pulsing light is quite enough to convince a possum they need a more desirable residence. There is now a small machine, about $89 worth, which I'm not naming as I haven't tried to it, but which is said to emit ultrasonic noise possums hate, as well as strobe lights.

A radio set to a sport's channel, or even a recorded match, set on loud between 2-4pm - prime possum sleep time - should work too, though you may need to repeat every few weeks. Any exciting football match should be successful. Do not try Mozart - possums enjoy anything melodic.

You could also fill the space with old tangled chicken wire - or whatever wire you can find to recycle - anything prickly and non-flammable. Tangled wire is not prime possum nesting material. Cover the floor in wire dish scrubbing pads, teased out so they are impossible to clamber over. Small dishes of mothballs may work, as will anything that smells both pongy and inedible, though remember that ringtail possums do sometimes eat old carcasses, so we are talking truly repulsive pongs here - and one that won't seep down to you.

Basically, be inventive. What can you add to your roof space that a possum will hate?

There is another way, of course. I know your backyard isn't a National Park, and yes you pay the rent/mortgage, and not the possum. But you might just consider accepting a possum family as welcome guests.

Lay down waterproof plastic so nothing odorous seeps down to your ceiling; add old blankets, plus perhaps a dog bed or any other bedding that can be removed and washed every few weeks. Leave out a few carrots, some apples, the celery tops and other possum delicacies. If you want to give them a treat, try tabouli with lots of garlic and a lemon juice dressing.

Grow extra fruit, veg and roses for possum snacks, too. Possums are small animals, even if their appetite seems disproportionately large.

Eventually you and the possums may even become friends, that rare and precious friendship between human and wild animal.

Just remember to be quiet between 2-4pm. And never cut down their loquat tree.