Spider Beetles

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Identification

  • Colour Reddish-brown or black to pale yellow or cream
  • Size From 2 mm to 5 mm long
  • Description Oval or cylindrical, with globular abdomens and hidden heads. They have six legs and a pair of long antennae.
  • Notes Resemble spiders upon first glance.

How to identify Spider Beetles

Though the different species of spider beetles vary in appearance, most bear a resemblance to spiders upon first glance thanks to their globular abdomens and the way their heads remain hidden from view when observed from above. Most species range in size from 2 to 5 mm and appear oval or cylindrical in shape. Each spider beetle has six legs and a pair of long antennae. The insects vary in colour from reddish-brown or black to pale yellow or cream, with distinctive markings that depend on the specific species.

Signs of an infestation

As spider beetles are very small, generally reclusive, and active primarily at night, humans are often unaware of the presence of the pests in buildings. The most telling sign of an infestation is the sighting of an adult spider beetle or a pupal cocoon. In addition, the foraging pests may leave behind accumulations of granular materials in pantries and around food supplies.

Spider Beetles Removal

If an infestation of spider beetles already exists in the home, the first step to removing the problem is tracking down the food source. Place sticky traps near known and suspected food sources to track the activity of the elusive pests. Any contaminated food should be promptly removed. For especially large infestations, seek the services of an experienced pest control professional.

How to prevent Spider Beetles from invading

Eradicating spider beetle infestations centres on discarding contaminated foodstuffs and eliminating access to other preferred food sources. As the pests feed on a wide variety of items and materials, preventative measures prove fairly challenging to implement. Purchasing airtight containers to store foods, vacuuming regularly, and removing rodent and bird nests from inside and around buildings are good places to start. For further assistance and control, consider contacting a pest control professional.

Habitat, Diet, and Life Cycle

Habitat

Spider beetles are largely cosmopolitan in distribution. Capable of remaining active in the cold and reproducing even when temperatures drop as low as 10º C, the insects live throughout the world, wherever human civilizations exist. Due to their scavenging nature and preferred food sources, spider beetles often infiltrate warehouses, mills, grain storage facilities, museums, and attics with rodent or bird nests. Additionally, the beetles exhibit a preference for moisture.

Diet

A noted stored product pest, spider beetles mainly consume grains. Common food sources include almonds, animal skin, beans, books, cereals, chocolate powders, corn meal, dates, dead insects, dried fruits, mushrooms, dried soups, excrement, feathers, figs, fish meal, flour, ginger, hair, leather, corn, nutmeg, older woods, paprika, rye and rye bread, seeds, silk, textile fabrics, wheat, and wool.

Life Cycle

Most species of spider beetles follow a similar reproductive and life cycle pattern. The insect goes through a complete metamorphosis and develops sequentially from egg to larva to pupa to adult. Eggs hatch within two to three weeks of being laid. Spider beetles typically complete three molts or instars during the larval stage and then spin cocoons in preparation for the pupal stage of the life cycle.

Once in the cocoon, the insect may pupate immediately or go into an extended diapause, which lasts as long as eight months. Though pupae usually reach adulthood within 20 days, the beetles remain in the cocoon for the duration of a month until they reach sexual maturity. Adults feed and mate after emerging and may live for several months. Females usually live longer than males and produce approximately two generations of offspring each year, depending on the temperature and humidity in the environment.

Commonly Asked Questions

Why do I have spider beetles?

Spider beetles feed on a massive range of products, including almonds, animal skin, beans, books, cereals, chocolate powders, corn meal, dates, dead insects, and dried fruits.

They also seek out mushrooms, dried soups, excrement, feathers, figs, fish meal, flour, ginger, hair, leather, corn, nutmeg, older woods, paprika, rye and rye bread, seeds, silk, textile fabrics, wheat, and wool.

Because of this wide range of potential food sources, spider beetles often infiltrate warehouses, mills, grain storage facilities, museums, and attics with rodent or bird nests. They tend to infest mouldy products that are old and high in moisture.

How worried should I be about spider beetles?

Spider beetles contaminate human food supplies and typically unclean, which can make food inedible in homes, and have serious economic consequences for businesses. Since they also eat inorganic material, they can destroy priceless artifacts in museums and storage.

But spider beetles are very small, generally reclusive, and active primarily at night, so humans are often unaware of their presence. They can also remain active at freezing temperatures, and produce two generations of offspring a year.

You can place sticky traps to catch these pests, but the only way to be sure you don’t have a large infestation of spider beetles is with the help of professional pest control services.

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