A true story and its source was the Australian Quarantine Inspection Service in Adelaide. A bloke and his family were on holidays in the United States and went to Mexico for a week.  An avid cactus fan, the man bought one-metre high, rare and expensive cactus there.  On arrival back home Australian Customs said it must be quarantined for 3 months. 

He finally got his cactus home.  Planted it in his backyard, and over time it grew to about 2 metres.  One evening while watering his garden after a warm spring day, he gave the cactus a light spray.  He was amazed to see the plant shiver all over, he gave it another spray and it shivered again.

He was puzzled so he rang the council who put him on to the state gardens people. After a few transfers he got the state's foremost cactus expert who asked him many questions.  How tall is it?  Has it flowered? Etc. Finally he asked the most disturbing question. "Is your family in the house?" The bloke answered yes.  The cactus expert said get out of the house NOW, get on to the front nature strip and wait for me; I will be there in 20 minutes. Fifteen minutes later, 2 fire trucks, 2 police cars and an ambulance came screaming around the corner.  A fireman got out and asked "Are you the bloke with the cactus?" I am, he said.  A guy jumped out of the fire truck wearing what looked like a space suit, a breathing cylinder and mask attached to what looked like a scuba backpack with a large hose attached. He headed for the backyard and turned a flame-thrower on the cactus spraying it up and down. After a few minutes the flame-thrower man stopped, the cactus stood smoking and spitting, half the fence was burnt and parts of the gardens were well and truly scorched.  Just then the cactus expert appeared and laid a calming hand on the bloke's shoulder. "What the hell's going on?" he says. "Let me show you" says the cactus man.  He went over to the cactus and picked away a crusty bit, the cactus was almost entirely hollow and filled with tiger striped bird-eating tarantula spiders, each about the size of two hand spans. The story was that this type of spider lays eggs in this type of cactus and they hatch and live in it as they grow to full size.  When full size they release themselves.  The cactus just explodes and about 150 dinner plate sized hairy spiders are flung from it, dispersing everywhere. They had been ready to pop.  The aftermath was that the house and the adjoining houses had to be vacated and fumigated: police tape was put up outside the whole area and no one was allowed in for two weeks. And here's what one of the spiders looks like sitting on a FULL SIZE dinner pl