How do you know if your rabbit has fly strike?

Fly strike is visible to the naked eye: if you see maggots half-burrowed in your rabbit's skin, or if you see holes in your rabbit's skin and movement under the skin, then your rabbit has fly strike.

If you suspect fly strike, bring your rabbit to the vet as soon as possible. Fly strike isn't something you can fix at home: even if you're able to safely remove all the maggots (which can be tricky, because if you burst one, it can release deadly toxins into your rabbit's body), your rabbit will still need medication in order to heal properly.

Any time you see sores on your rabbit, bring her to the vet as soon as possible. The smallest cut, no matter what the cause, can lead to infection and abscess.

Any time you see bugs or parasites in your rabbit's fur, bring her to the vet as soon as possible and fix your rabbit's habitat so that she's no longer exposed to these threats. The vet should examine your rabbit to ensure there's no more bugs/parasites affecting the bunny and, if necessary, provide treatment if there is a parasite infestation.

Any time your rabbit is "depressed" (just laying there, not active like before, not interested in cuddles or food; may be hiding; may be grinding teeth in pain; etc.), this is a sign of advanced illness and the rabbit should see a vet immediately -- if your usual "rabbit savvy" vet is not open, then bring it to an emergency 24/7 vet.

See the related questions below for more info and helpful links.