Buzz McCallister kept a tarantula, called Axl, in his bedroom, in a fish tank on a loose-shelving unit. When Kevin was left home alone and attempted to climb the shelves to get to Buzz's life savings, his weight accidentally broke them and came tumbling down. While Kevin dusted himself down and grabbed the savings, the tank had also shattered, letting Axl escape.
When Kevin cleaned himself in the bathroom, Axl crawled next to the toilet. Later, when Kevin prepared booby traps in preparation for the night ahead, the tarantula was seen wandering the house in various locations (on a wooden shelf, running across the front room etc.) When the Wet Bandits fell prey to Kevin's traps, Marv dodged the tripwire, leapt and grabbed Kevin by the leg as he tried to escape to the third floor. Kevin saw the tarantula crawling along the steps and tried to reach for it. The tarantula remained docile when he reached for it and Kevin, able to pick up the tarantula, placed it on Marv's face, causing Marv to scream hysterically and gave Kevin a chance to reach the attic. Frightened, Marv, still shrieking, threw the tarantula on Harry (who was unconscious), grabbed his crowbar and Harry, who had awakened, asked Marv what he was doing. Marv told Harry not to move, and while the tarantula was still on him, Marv accidentally hit Harry in the belly with the crowbar, only missing the tarantula by inches.
- It is never confirmed whether Axl was male or female. Buzz assumed it was male, as he says at the beginning of the movie "He just ate a whole load of mice guts; he should be good for a couple weeks".
- The novelization reveals the tarantula's name to be Axl.
- A species of tarantula featured in the film has for years been presumed to be the Chilean Rose Tarantula (also known as Grammostola Rosea) since this species is frequently used in movies because of its compliant nature and wide availability. However, the actual species used is now reportedly to be the Costa Rican Zebra Tarantula (Aphonopelma Seemani), as hinted by its orange web spinnerets and striped legs clearly visible on its legs throughout the film, a distinctive feature of this species.
- Axl does not return in Home Alone 2: Lost in New York because Kevin is not left at home this time as he is finally travelling with his family and they go on vacation in two different places: New York City and Miami, Florida.