Be sure to bring both popcorn and bug spray to “Mosquito,” a film about how something tiny can be such a big threat.

“Mosquito” is one of several health-oriented features being shown as part of the AFI DOCS Documentary Film Festival June 14-18 in Washington and Silver Spring. And it’s a reminder that although the Zika epidemic has officially just ended in Puerto Rico, that’s probably not the last we’ll hear of infants whose microcephaly was caused by the virus. Director Su Rynard lets viewers experience the heartbreak of that neurological condition through a Puerto Rican family that holds monthly birthday parties for their tiny, afflicted son because doctors say he probably won’t make it through his first year.

There’s nothing new about mosquitoes spreading horrific diseases, explain a variety of international experts, including one with a cute model of the insect on his desk. (He uses it to teach a group of African children about a new technique for mosquito-proofing homes.) If you’ve got an exposed patch of skin, there’s a female mosquito out there that would love to make a hole, spit some infected saliva into it and then slurp your blood. In the process, she could pass on Zika, or perhaps dengue, chikungunya, West Nile, malaria or something else scientists have yet to discover.

She’s more likely to track you down than ever before. Climate change turns out to be great news for mosquitoes, particularly the fearsome Aedes aegypti variety, now free to move into formerly inhospitable areas. Washington’s claim to fame in the film: It’s home to the northernmost population of A. aegypti that stick around through the winter. Scientists say they rely on the city’s tunnels for protection. Thanks, Metro!

So why don’t we just kill the bugs off? If only it were that easy. Chemical spraying leads to resistance and also to serious ecosystem complications, including the death of bees, butterflies and other key pollinators. The documentary highlights the development of a new biotech strategy to create male A. aegypti mosquitoes with a special trait: They mate as usual, but their offspring die. Early results are promising.

But if you can manage to sleep after watching this, you’ll still want a net over your bed.

The international premiere of “Mosquito” will be Thursday at 6:30 p.m. at the Newseum.