Transcript:

Today on Animal Fact Files we’re discussing weevils. There are nearly 100,000 described weevil species. They're generally split into two big groups: the true weevils who make up over half the living weevil species, and the prehistoric weevils. These groups are further split into many more groups, however, with a few exceptions, true weevils can be told apart from prehistoric weevils by their antennae. True weevils have an elbow-like bend in their antennae while prehistoric weevils have straight, unbent antennae. There are also animals commonly known as weevils that aren't part of the weevil superfamily. These may sport the long rostrum, or snout, seen in true weevil species, but are otherwise unrelated. Weevils are also commonly known as snout beetles for this long rostrum.

Some weevils are strong fliers and others can barely fly at all. Some have grooves they can tuck their antennae into and others do not. Some come in neutral colors while others can be brilliant colors. Some are less than a quarter of an inch long (6mm) while others are more than three inches (76mm) in length. In some, the rostrum is half the body length and in others it's quite short. In some species the females are longer than the males and in other species, it’s the opposite; so it's difficult to give a general overview on this diverse group of animals! In fact, these are some of the most diverse insects in the world!

Most weevils are plant eaters. Many have a preference for a single species or related group of plants. Both adults and larvae eat. Unlike skink bugs that pierce their meals, adult weevils have chewing mouthparts at the end of their rostrum. These are used for boring into plant material and also allow for digging out egg chambers in food sources. Some eggs are laid in plants and sealed inside. The larvae then eat the plant from the inside out until they become an adult and chew themselves out of the plant!

Weevils begin life as an egg. Most female weevils have a longer snout than the males so they can more easily bore into plants where they will lay their eggs. These hatch a few days later into larvae that immediately begin eating. Weevil larvae usually prefer a specific plant species and may specialize on a single part of a plant, like the flowers, roots, or leaves. Weevil larvae are white and grub-like. Like scarab beetles, they're redheaded and c-shaped. The larvae eat and grow for a few weeks before pupating. After a few days, the adult emerges. Adults attract each other with pheromones and there may be multiple generations in a single year. The entire metamorphosis process can take less than a month and they may live months to a year depending on the species.

Weevils live in all kinds of habitats and stick to places where the plants they prefer to eat grow. They can be found in grasslands, open areas, arid regions, and rainforests throughout most of the world. Many have been introduced to non-native areas by humans who unknowingly transport them through shipping operations. Some species are considered pests because they eat human agricultural plants. Outside of this, these beetles aren't dangerous to humans. They can sometimes be found in human homes but often leave on their own. Natural predators to weevils include predatory nematodes, beetles, and spiders.

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