Specimens primarily from, or deposited into, either the TAMUIC or the UTIC collection.
Weevils are a ubiquitous type of beetle belonging to the superfamily Curculionoidea With over 60,000 species, weevils can be found all over the world and in a diverse range of habitats While the various types of weevils may appear similar on the surface, they actually display an impressive range of unique adaptations and behaviors. In this article, we’ll take a deep dive into the numerous types of these fascinating beetles.
What Are Weevils?
Weevils are a type of beetle characterized by an elongated snout and small, pear-shaped body. The most distinctive feature of weevils is their long snout, which houses their mouthparts and antennas. The snout allows them to chew and bore into various foods and plants. Weevils belong to the Curculionidae family, one of the largest families of beetles.
There are over 60,000 known species of weevils around the world. They are found on all continents except Antarctica. Weevils are plant eaters and are commonly considered agricultural pests. However, only a small percentage of weevil species cause significant damage. Many play beneficial roles in their ecosystems.
Diverse Species with Unique Adaptations
Weevils display an incredible diversity of form and function. They have adapted to feed on a wide variety of plants in both larval and adult form. Different species have evolved distinct snout shapes and mouthpart structures to allow them to consume their target plant materials. Their small size, cryptic coloration and protective scales or hairs help them blend into their surroundings and avoid predators.
Some weevils are wingless, while others have fully developed wings or reduced wing structures. Flight capabilities range from strong fliers to weak gliders. Some weevils have even lost the ability to fly entirely. Legs also vary in length and structure, with some adapted for swimming or grasping host plants. This amazing variety allows different weevil species to thrive in habitats from rainforests to deserts.
Weevil Life Cycle
Like all beetles, weevils undergo complete metamorphosis with four life stages: egg, larva, pupa, and adult. The larvae typically feed externally on plant foliage or internally on stems, roots, or seeds. As larvae mature, they construct a pupal cell around themselves and undergo metamorphosis.
Adults emerge from the pupal cell ready to reproduce. In some species, adults live only long enough to mate and lay eggs. In others, adults live for months or even years, continuing to feed and lay multiple batches of eggs. Overall, weevils can produce impressive numbers of offspring over a single generation.
Major Types of Weevils
With so many species, classifying weevils can be a daunting task. Scientists have grouped them into many subfamilies and tribes based on shared physical and genetic traits. Here are some of the major types and most notable species:
Grain and Seed Weevils
- Granary weevils: Feed on stored grains like wheat, rice, oats. Cylindrical shape, long snout.
- Rice weevils: Major pests of stored rice. Reddish-brown with spots on wings.
- Maize weevils: Resemble rice weevils but larger. Feed on corn.
- Bean weevils: Various species feed on beans, peas, and other legumes.
Root and Foliage Weevils
- Black vine weevils: Larvae feed on plant roots, adults on leaves. Pests of ornamentals.
- Strawberry root weevils: Feed on strawberry roots and leaves. Overwinter in soil.
- Leaf-rolling weevils: Larvae roll and feed inside leaves of plants like apples, grapes.
Weevils of Agricultural Significance
- Boll weevils: Serious cotton pests across the southern US, Mexico. Reduced yields.
- Alfalfa weevils: Larvae and adults consume alfalfa plants. Diurnal, active in daytime.
- Fuller rose weevils: Chew rose leaves and buds, also attack fruit trees.
Weevils with Beneficial Roles
- Seed-eating weevils: Help control invasive plants by consuming seeds.
- Pollinating weevils: Carry pollen between flowers as they feed on nectar or petals.
- Predatory weevils: Larvae or adults prey on pest insects like aphids, caterpillars.
This is just a small sampling of the incredible diversity found across the various types of weevils. From tiny species a few millimeters long to giant weevils over an inch in size, these beetles have adapted to thrive in a vast array of niches worldwide. Their importance as agricultural pests led to extensive research that continues to reveal new insights into weevil ecology and evolution.
Nemonychidae – Pine Flower Snout Beetles
- Ormiscus
Attelabidae – Leaf Rolling Weevils
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Attelabinae – Leaf-rolling Weevils
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Rhynchitinae – Tooth-nosed Snout Weevils
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Eugnamptus
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Haplorhynchites
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Temnocerus
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Pterocolinae – Leaf Roll Thieves
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What Are The Different Types Of Weevils? – Insects and Invaders
FAQ
What do weevils turn into?
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1. Egg:Weevils begin their life as eggs, often laid in plant tissues or stored products like grains.
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2. Larva:The egg hatches into a larva, which is a grub-like stage where the weevil feeds.
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3. Pupa:The larva eventually enters the pupa stage, where it undergoes significant changes, sometimes forming a cocoon.
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4. Adult Weevil:Finally, the adult weevil emerges from the pupa. This adult weevil has a hard outer shell, wings (in some species), and a long snout.
Why am I finding weevils in my house?
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Food Source:Many weevil species, like the rice weevil, feed on stored food products, and homeowners may unknowingly bring them in through infested packages of beans, popcorn, cereal, or nuts.
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Seeking Shelter:Weevils, especially during hot and dry weather, look for shelter in buildings, entering through cracks or openings around foundations, doors, and windows.
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Moisture:Some weevils are attracted to moisture, and may enter homes seeking it.
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Infestations Outside:Weevil infestations can start outside in fruit trees or gardens, with the pests then entering the home through cracks and openings.
What kills weevils instantly?
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Insecticide Aerosols:
- Pyrid: is a ready-to-use insecticide aerosol that controls a wide range of indoor and outdoor pests, including weevils.
- It interferes with the weevil’s central nervous system, resulting in a quick knockdown within minutes.
- When treating cracks and crevices, spray in quick bursts, about 1 second of spray per foot.
- Pyrid does not leave a residual, but it is an excellent contact spray with a powerful knockdown and quick kill.
- Pyrid: is a ready-to-use insecticide aerosol that controls a wide range of indoor and outdoor pests, including weevils.
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Extreme Temperatures:
- Freezing: Place infested food items in the freezer for a few days to destroy the pests.
- Heating: Heat infested food to near-boiling temperatures to quickly eliminate them in less than an hour.
- Freezing: Place infested food items in the freezer for a few days to destroy the pests.
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Other Methods:
- Vinegar: Use a vinegar and water spray solution to eliminate weevils that are on the surface of food items.
- Vacuuming: Thoroughly vacuum the shelves, including the cracks and crevices where weevils may hide.
- Wiping Down Surfaces: Wipe down shelves with hot soapy water or a disinfecting spray, then wipe again with white vinegar.
- Professional Pest Control: For severe infestations, consider hiring a professional pest control service.
- Pheromone Traps: Use pheromone traps to lure weevils using attractants.
- Airtight Containers: Store food in airtight containers to prevent weevils from reaching food sources.
- Vinegar: Use a vinegar and water spray solution to eliminate weevils that are on the surface of food items.
Should I throw out flour with weevils?
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Why throw it out?
- Contamination: Weevils can contaminate flour with their eggs, larvae, and feces, making it unsafe to eat.
- Difficult to remove: It’s very difficult to physically remove all the insects and their byproducts from the flour, even with sifting.
- Potential for re-infestation: If you try to keep the flour, the weevils may continue to multiply and infest other food items in your pantry.
- Unpleasant experience: The sight of weevils in your flour can be unsettling and make you hesitant to use the flour.
- Contamination: Weevils can contaminate flour with their eggs, larvae, and feces, making it unsafe to eat.
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What to do instead?
- Dispose of the flour: Seal the infested flour in a bag and throw it away.
- Clean your pantry: Thoroughly clean your pantry shelves and vacuum any cracks or crevices where weevils might hide.
- Inspect other food items: Check other dry goods in your pantry for signs of infestation.
- Store food properly: Store flour and other dry goods in airtight containers to prevent future infestations.
- Dispose of the flour: Seal the infested flour in a bag and throw it away.
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What are weevils?
- Weevils, also known as flour bugs or long-snout bugs, are tiny beetles that infest flour, rice, cornmeal, and other dry goods in the pantry.
- They can enter through windows or small cracks in the home and seek out open food containers.
- Weevils, also known as flour bugs or long-snout bugs, are tiny beetles that infest flour, rice, cornmeal, and other dry goods in the pantry.