A line of ants hurries forward, bringing in grain for the harvest. Suddenly a leaf falls into its path.

Panic sets in. What will they do? Where will they go?

Not to worry, cries their superior, "We're all trained professionals here." He leads them around the leafy green obstacle, noting in retrospect that "This was nothing compared to the twig of '93."

A Bug's Life -- the latest video release from Walt Disney and Pixar Animation Studios, makers of the megahit Toy Story -- goes both up and down from there.

On the upside, A Bug's Life has a world view and a sense of epic adventure -- albeit on a miniature scale -- that would have seemed out of place in Andy's bedroom.

The story revolves around Flik, a clever inventor ant whose contraptions have a way of backfiring on both him and his colony. His harvesting machine, for instance, designed to bring in grain by the bushel, accidentally destroys the cache of foodstuffs the ants had prepared for their nemesis, an evil grasshopper named, appropriately enough, Hopper. When Hopper and his gang arrive to find their tribute gone, they threaten revenge upon the defenseless ants.

Once again, Flik tries to save the colony, this time by enlisting some warrior bugs to fight off Hopper. But once again he comes up short, enlisting instead a failed circus troop that sizes up the situation much faster than Flik ever could have.

It's a very funny premise for a film and A Bug's Life directors John Lasseter and Andrew Stanton work it out to its perfectly illogical conclusion, pausing along the way for some unforgettable set pieces: Hopper playing darts using mosquitoes; the circus performers doing death-defying battle with a hungry bird; Flik's own mechanical bird being rowed by the ants as if it were a slave ship.

Moreover, the animation is seamless, the color scheme stunning and the voice casting perfect: Kevin Spacey plays Hopper as half motorcycle thug, half CEO; Julia Louis-Dreyfus brings just the right touch of anxiety to Princess Atta, the queen-to-be in training; David Hyde Pierce gives us good schtick as a walking stick; and Phyllis Diller as the old queen is simply one great ant.

On the downside, however, A Bug's Life lacks the sustained drive of A Toy Story, largely because it lacks the strong hero of the latter film. Flik (voiced by Dave Foley) says he "only wants to make a difference." That's a selfish motivation -- one that works in a fable of foibles like Toy Story, but won't sustain an epic, even an ant-sized one.

Worse, Flik gets bogged down in sentimental cliches, like his tale of the seed growing into a mighty tree, and outright self-pity when he's driven from the colony. As a result, A Bug's Life falls into the age-old Disney domain of eye-popping extravaganzas that depend on their secondary characters to keep the film afloat and their audience involved.

There's nothing wrong with that, of course. It's just that we know there's better. Toy Story has told us so.