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Identification

2 Posts tagged with the id tag
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Other names: Drugstore beetle, Bread beetle

 

Classification

Class             Insecta

Order             Coleoptera

Family            Anobiidae

 

The Bread beetle, Stegobium paniceum, also known as the Biscuit beetle (or the Drugstore beetle in the U.S.A.) is one of the commonest pest insects of stored food. It is able to feed on a variety of plant and animal products including bread and flour and even hot spices and drugs. However, this beetle is not harmful to health and despite its close resemblance to the Common furniture beetle or Woodworm beetle (in the adult stage), it does not feed on wood.

 

Identification

The adult beetles are usually noticed first.  They are small, between 2 and 4 mm in length, reddish-brown and, under magnification, reveal fine grooves running lengthways along the wing cases.  Furniture beetles (or Woodworms) are similar but are somewhat larger and darker and their antennae are shorter than the legs (in Bread beetles the lengths are similar). There are three flattened segments at the tip of antennae. The head is partially hidden by the pronotum (the plate that covers the upper part of the thorax). Biscuit beetles have large dark eyes.

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            Dorsal view                     Lateral view                  Ventral view       Biscuit (L) and Furniture beetle (R)

 

Photo credits: Siga / Wikimedia Commons. Line drawings © The Natural History Museum.

 

 

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Possible confusion

 

Furniture beetle (woodworm)

 

Anobium punctatum

Somewhat larger and darker brown, antennae shorter than legs.

Pronotum with obvious ‘hump’ like a monk’s cowl.

Larvae bore into wood, where they feed for 3-5 years.


Photo credits: Siga / Wikimedia Commons.

 

 

 

 

 

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Possible confusion

 

Cigarette beetle (Tobacco beetle)

 

Lasioderma serricorne

Antennae with many serrations, while Biscuit beetle has three large ones at the tip. Has much weaker punctures on the surface of the wing covers (elytra). Eyes easier to see from above. Different shape of pronotum.

 

Photo credits: Kamran Iftikhar / Wikimedia Commons

 

 

 

 

 

 

Distribution and habitat

The Biscuit beetle occurs in houses, stores, warehouses and kitchens throughout central and northern Europe, including the UK, sometimes in very large numbers. It is known as a cosmopolitan species.

 

Life cycle

In common with other beetles, this species passes through four life‑stages: egg, larva, pupa and adult (pictured below).  The speed of development through the life cycle depends on temperature, moisture, quality and abundance of food.  In cool temperatures (below 15ºC) there is only one generation per year, in moderate temperatures two, while at higher temperatures (above 23ºC) there may be five or more.larva.jpg

 


Eggs are laid by mated females on or near the foodstuff.  When the larva emerges from the egg, it is less than 1mm in length. In its search for food, it may bite into packaged or hidden food sources. The larva increases in size and, at about 5mm in length, it enters the pupal stage.  Before emergence as an adult beetle, a minimum of nine days is spent as the pupa in an oval shaped cell moulded by the larva using the food material.


Damage and control

Because the Bread beetle larva thrives in dark, warm, undisturbed places, it is essential to search thoroughly for the food‑source of the larva if adults are found wandering around.  Rarely-used dried-foods such as flour or spices are often the source of an infestation. Removing disused and old foodstuff should eliminate an infestation.

Adult beetles may be seen around fire‑places and air vents with no apparent food‑source available. These are likely to have come from nests of wasps or birds in the attic.  Beware also of bread in fire‑places that has been dropped down the chimney by birds.  With suitable hygiene, and by preventing access into the attic by nest‑builders, the successful eradication of this pest should be assured.

 

To find out more:

Info sheet on Cornell University website:

http://idl.entomology.cornell.edu/files/2013/11/Cigarette-and-Drugstore-Beetles-2014-ocf7nv.pdf

Another info page on University of Florida Institute of Food and Agricultural Sciences:

http://entomology.ifas.ufl.edu/creatures/urban/stored/drugstore_beetle.htm

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You only have to browse through the Fossils and rocks forum to see how many of the suspected fossils put on there turn out to be something completely different! Fossil eggs, bones, turtles, ferns, footprints, you name it, natural rock and mineral processes can mimic it. We call these natural rock and mineral specimens that resemble or are mistaken for fossils "pseudofossils". This post doesn't seek to go through the most common look-a-likes, but if you google "pseudofossil" you will find many excellent guides out there.

 

This post is just some of my personal favourites from the last year. Fun and amazingly co-incidental pseudofossils are one of my favourite parts of my job in Earth Sciences identification.

 

2010-2444 mineral thought to be fossil bird head 003.jpg

"Fossil bird head"

 

It's got everything - neck, beak, even an eye. But this shape is created by the growth of a mineral upon the rock surface.

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"Fossil shark"

 

This shark shape, silhouetted in white against the dark background, would have me swimming for my life if I saw the silhouette peaking out of the sea. But it is just a chance area of cleaner white Chalk against a backdrop of Chalk discoloured by dirt and moss.

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"Fossil fish"

 

I can see what they mean, it looks like a guppy with a long flowing tail and fin. But this is a type of the rock flint known as banded flint. Banded flints form a series of roughly parallel lines such as this, which can create all sorts of misleading shapes. The cause is still not fully understood but the movement of water and silica through the flint is thought to be involved.

 

The rock flint can mimic any kind of fossil you can think of - bones, eggs, whole heads and bodies, you name it. Look out for a blog all about the wonders of flint coming soon!

 

2011-0058 dinosaur head pseudofossil 001.jpg"Fossil dinosaur head"

 

If this were a dinosaur, I can even see what kind it would be - one of the duck-billed hadrosaurs I reckon. Sadly, this is just the shape of the lump of rock, that had probably been exaggerated by weathering.

 

 

While writing this I've realised that these pseudofossils do have something in common after all. They all demonstrates one of the key things to appreciate when looking for fossils: don't look for the overall shape of an animal. This is because the soft parts of animals like muscle and skin only fossilise very rarely and in unusual conditions. You can assume you won't come across soft part preservation without knowing what to look for and where to look. To find fossils, look for the hard parts such as bones and shells, and bear in mind these are most often broken, mixed up and/or isolated.

 

Although we can say what these aren't, the hardest question to answer is, so why did the rock or mineral form or weather into exactly that shape? There are millions of rocks out there and so even if such coincidental resemblences are rare, there will still be plenty of pseudofossils. And of course those are the rocks that are going to catch your eye and get picked up.

 

So what should you look for? This page on our website has some good information and links for fossil hunting advice. And of course we will be happy to see whatever you find, whether rock, mineral or uncannily-vegetable-shaped-rock on the rock and Fossil forum here.

 

Happy fossil - and pseudofossil - hunting!