Ever Seen a Bug Use Its Nose Like a Power Tool? Meet the Weevil

Have you ever seen a weevil up close before? These tiny insects are famous for their ability to drill holes. A weevil drilling a hole into an acorn is a fascinating process to observe. But why do they do this, and what purpose does it serve? Check out this video by Granny Beaver of a weevil drilling into an acorn. Then read on to learn why weevils do this and what purpose it serves.

How Weevils Drill

To start understanding how weevils drill, we have to know their anatomy. Weevils have a structure called a proboscis, which is a long, flexible nose or snout found in certain animals, known for its length and mobility. For example, what many people call a trunk on an elephant is actually a proboscis. A weevil’s proboscis is specifically adapted for drilling and burrowing into acorns. Weevils are around 3/8 of an inch in size, with their snouts being almost as long as their entire bodies.

So, how exactly do weevils burrow? Weevils use their snout to open the acorn by drilling and burrowing, continuously rotating it back and forth until they reach a sufficient depth. At the end of the weevil’s snout are sharp mandibles that do the actual cutting. By using the sharp ends of their mandibles along with the pressure they apply, weevils are able to drill holes.

Why Do They Drill?

Weevils drill holes for two primary reasons: nutrients and reproduction. Obtaining nutrients is a primary reason for drilling. While drilling, the weevil uses its mandibles at the tip of its snout to chew through the acorn. Weevils chew on the plant material, ingesting it while they drill. This allows weevils to get the nutrients needed for life through drilling into different foods such as acorns.

Reproduction is another main reason that weevils drill holes. The hard, sturdy surface of an acorn makes it a safe place for weevils to lay their eggs. Because of this, weevils, after drilling a hole, will rotate their body to position their ovipositor, or a tube-like organ that female insects use to lay their eggs, above the hole. The weevil will maneuver its ovipositor inside the hole they have drilled to lay their eggs, allowing for safe hatching and growth.