“The Love Bugs,” an award-winning short documentary, answers that question. Co-directed and produced by Allison Otto and Maria Clinton, it follows the nonagenarians as they face old age, health problems and the wind-down of their scientific careers.

The O’Briens decided to donate more than 1,200 drawers of preserved insects to Arizona State University, and endowed professorships devoted to identifying and naming new insect species. It’s a massive undertaking that more than doubled the university’s collection, and a bittersweet one for the devoted couple.

The film explores their relationship, their bugs — including about 1 million weevils — and what the collection means to science. The university is digitizing the painstakingly preserved collection, which contains previously unknown species. Charlie O’Brien identified over half of the insects in the collection, a process that can take hundreds of hours per species.

But the documentary is about more than insects. It’s about love: Love of science, love of research, love of one another. It’s a sweet glimpse into an illustrious dual career that took off on the couple’s honeymoon, which was spent collecting insects in Canada.

And it gives a peek into the future of the O’Briens’ bug-laced legacy. One of the movie’s best moments comes as the team moving the collection from the O’Briens’ home catches a glimpse of some colorful specimens and bursts into excited chatter. It conveys the wonder and scientific value the couple have passed on to others — and what they’ll leave behind when they are gone.

“The Love Bugs” is now streaming free on the PBS series POV Shorts.