Watch Weevils Invade California Palm Trees

Josh Cassidy/KQED
Josh Cassidy/KQED / Josh Cassidy/KQED

California is known for its palm trees. Though it only has one native palm species—the rest are imported—the carefully trimmed trees are an instant visual that reads "paradise." Sadly, some palms are now being eaten by weevils.

The South American palm weevil is a big lumpy beetle with a mission: burrow into palm trees and lay eggs. They favor the Canary Island date palm, sometimes called the "pineapple palm" referring to its distinctive shape after pruning.

Female palm weevils drill into the apical meristem ("heart of palm" to foodies) to lay eggs. The newly hatched weevils start life in a bountiful environment, surrounded by food and water. They eat the trees' heart out, leaving a mushy ruin in their wake. Then the larvae proceed with their lifecycle, maturing inside cocoons they make from leftover palm fibers. When they hatch and fly on, the cycle repeats.

This slow escape can kill the tree, as the apical meristem is where the tree sprouts new leaves. In many cases the weevils leave the tree in a state of severe injury, with a characteristic wilt to its existing leaves.

Finding these weevils isn't easy—once they've burrowed in, they're basically undetectable until the damage is done. The current best practice for preventing their spread is to treat palm trees with anti-weevil pesticides. As the weevils begin to invade San Diego, scientists are tracking their spread.

In the video below, Deep Look gets up close with these palm weevils and the scientists studying them. This was shot in 4K Ultra HD, so you can see the creepy little bugs in all their H. R. Giger-style glory.

If video isn't your thing—or you just want more discussion of the science—read this KQED Science blog post.