The Weevil

The weevil is a small insect that usually occupy the insides of grains or fruits. They belong to the family Curculionidae and have over 60,000 species.

HOW TO IDENTIFY WEEVILS


a weevil on a leaf

Weevil

They are also known as ‘snout beetles’ because they have a snout with the mouth at its end. This snout is the reason for their success. It is used to penetrate into grains and fruits, and also to burrow holes in which to lay eggs. Different species differ in the appearance of their snout, some have rounded and some have tubular snouts.

Sometimes, their snout is even longer than their head. Some species do not have a distinct snout and have a cylindrical body. They are usually found in fields, gardens, and orchards.

Weevils may have an oval or elongated body. Some of them lack wings, but others can fly fairly well such as rice weevils. They range in length from 6mm to 80mm. They have paired antennae. Weevils are usually dark-colored, brown or black, but some species bear strikingly bright colors.

Weevils feed on plant material. Their larvae are very particular in this regard, because they may only eat certain parts of the plant, such as seeds or fruits. The adult larvae have fewer specifications when it comes to food. Weevils may sometimes find their way in your food products or stored grains. Aside from eating them, they also contaminate these food products with their feces and sloughed off skin, thus rendering it inedible. Weevils may act as predators, scavengers or simply herbivores but some have also shown parasitic behavior.

HOW DO YOU GET WEEVILS


Weevils feed on plant material, therefore plants and trees near your house can be a major cause for these pests to find their way into your home. It isn’t difficult for them to creep inside through cracks or holes.

Packaged food products that are bought in bulk are an important source of weevils. They may contain the weevil’s eggs which are almost naked to the human eye and impossible for you to detect. They’re mostly found inside food grains, such as rice and cereals.

HOW TO GET RID OF WEEVILS


The first line of action when you find weevils in your house in stored food is to eliminate the food source. Then, clean your entire house carefully with a vacuum, not missing any item of furniture. Dispose the contents of the vacuum cleaner outside your home in a container, so that they don’t come back in. Fumigates or pesticide sprays are also used when there is an immediate need for eradication of these insects or when the infestation gets out of control. But this method is discouraged because it is detrimental to the health of human beings.

To prevent the invasion of weevils inside your homes close all the doors and windows carefully. Then, check for cracks or holes inside the doors or window frames. Seal them in case you find any.


Life Cycle of Weevils


Weevils usually reproduce bisexually. But in some parthenogenesis may occur, which is a process where new offsprings are produced without fertilization. The life cycle of a weevil is comprised of the following stages:

Egg:

The male and female weevils mate and female gives eggs. The eggs are usually laid on plants so that the larvae can feed on them.

Larva:

After almost a week, the eggs hatch and larvae emerge. They keep feeding and after a while, their cuticle splits and a new larger and harder one is formed in its place. This process is called molting and it may take place about three to five times. The cuticle keeps hardening and darkening by a process called sclerotization and melanization.

Pupal:

After a few molts, the pupa emerges. This takes place after a short nonfeeding stage called prepupal stage. The pupa resembles the adult but it is soft and pale. All of its appendages are folded towards the inside. The wings are kept folded in a sac called wing bag. The pupal stage can last for more than 3 days.

Adult:

After the pupa sheds its skin the adult weevil emerges and spreads its wings. Its outer covering is now fully hard and does not harden anymore. It is also colored now. The transition from larvae to adult may take 21 to 27 days, or sometimes even longer.


Purpose of Weevils in Ecosystem


Most weevils act as pests. They bore into tree trunks, seeds, and fruits. They damage the vital part of the trees. Moreover, they consume the roots of plants thus stunting their growth. Infestations on a large scale can also result in crop failure. The insects that damage the wood furniture in your homes are mostly these weevils. They erode lumber too. In addition to this, they act as scavengers and consume dead plant material. For this very reason, they have also been able to destroy museum artifacts. They damage carpets and clothes too. It is advisable to do through check-up of your residence or workplace for these pesky pests before opening up for shop.

Some species of weevils help control populations by feeding on insects and their larvae. A very common example is that of a ladybird beetle that eats the aphids that harm plants.

Certain species of weevils that live in the moss forests show a special sort of association known as epizoic symbiosis. A wide variety of fungi grow on the back of these weevils and certain mites feed on this fungal growth. It also carries the spores of the fungi from one place to another.


Weevil Facts


Some interesting facts about weevils are listed below:

  • A single female weevil can lay up to 300 eggs at a time.
  • They have elbowed antennae.
  • They cannot reproduce in a temperature less than 15°C
  • Weevils have endosymbiotic bacteria living inside their gut to help them digest food.
  • They depend on their cuticle or exoskeleton for protection.
  • The male weevil may have a snout three times as large as that of a female.