Big Beetle Bonanza

This ain't no beetle drive! To celebrate National Insect Week join one of our ecologists, Adam Mantell, to discover fascinating facts about beetles. Did you know there are over 2,000 species in Ireland alone!

Three days a week I’m a part-time ecologist at Ulster Wildlife.  The other two days a week I do freelance entomology (insect identification and ecology).  The variety is fantastic, and sometimes my two jobs overlap, and I find rare or interesting species while I am working.   

 

Fascinating Beetle Factoids 

 

While on Covid 19 lockdown at Ulster Wildlife, I am a bit less busy than normal and I was asked to write a blog about beetles. I wasn’t immediately sure what the lovely folk reading this blog would want to know about.  You might be interested to hear about some of the more unusual ones that I’ve found, but maybe start with a few fascinating factoids! 

Here are my fascinating beetle factoids: 

  • Beetles are amazingly diverse and possibly the most successful groups of animals.  More than 400,000 have been scientifically described and named and they make up 25% of all known life forms.  There are 83,000 species of weevil alone. Estimates suggest that there may be as many as 2.1 million species in total if we could count all of them. 

  • In Ireland there are over 2,000 species and roughly twice that number in Britain. 

  • Their wing cases (elytra) are modified hardened wings that protect the squishy body underneath.  Many species have lost their wings altogether and cannot fly. 

  • Over 300 species of beetle are eaten by people around the world.  Even if you think you haven’t eaten any beetles, you have. They are a common contaminant in many foods like flour. 

  • The heaviest beetle is the goliath beetle which weighs up to 100g (like a bag of sweets) and can be up to 11cm long. Imagine finding one of those in your house! 

  • Beetles have been on earth for at least 300 million years. 

  • The Egyptians revered the scarab or dung beetle because of the similarity between the rising sun and the beetle rolling balls of dung. 

  • Burying or sexton beetles have a particularly interesting, if gruesome life cycle.  They can detect carcases of small mammals from over a kilometre away using their sensitive antennae. They are one of the few beetles that look after their young; first they bury the carcase and sterilise it with special antimicrobial secretions from glands in their head.  Once hatched the larvae beg the parents for food, who feed them with a special regurgitated liquid.   The parents are able to tell how many young the corpse will support, and if there are too many they will cull some to enable the rest to survive.  On larger corpses a number of adults work together to feed their young communally. In a final twist, the adults also carry mites on their body from corpse to corpse.  The mites are useful to the beetles as they don’t feed on the corpse itself, but on the eggs and larvae of other animals that would!  Just imagine having your own army of 8-legged friends to look after your food! 

Large copper dung beetle rolling a ball of dung

Large copper dung beetle rolling a ball of dung - Bernard DUPONT

Military Beetles

 

As part of my job at Ulster Wildlife I am lucky enough to spend time helping the Ministry of Defence look after the firing ranges at Ballykinler and Magilligan.  Over the last few years I’ve found quite a few rare and interesting beetles. Here are a few details about some of my favourites. 

This beetle is called Gonodera luperus and is quite common at Magilligan, but very strangely until I spotted it in 2016 it hadn’t been seen in Ireland for 100 years.  In fact Magilligan is the only place it has been seen in Ireland, but it is quite common in Britain! 

We’re not 100% sure what this species feeds on but as it is normally a woodland beetle it is likely to be feeding in the stands of blackthorn. 

Gonodera luperus. Black looking beetle with brown legs

Gonodera luperus - Udo Schmidt from Deutschland 

Lebia cruxminor

 

Next up is another beetle from Magilligan, going under the strange name of Lebia cruxminor.   

Not only does it have a strange name, it also has strange and rather secretive habits.  It is very rare across Europe and is red-listed for protection.  The larvae of this beetle are thought to parasitise another beetle called Galeruca tanaceti.  Normally found in wet grassland in Ireland, this record is unusual in coming from much drier dune grassland, and is 100km away from the next nearest record. 

Lebia cruxminor - brown and black spotted beetle on a white flower

Lebia cruxminor - By AfroBrazilian

The Tortoise Beetle Group

 

The next beetle is an unusual looking thing.  It is called Cassida nobilis and belongs to the Tortoise beetle group.  The striking tortoise shape and the pair of golden lines are quite characteristic.  It lives among plants and debris along the upper part of the shore.  Its distribution in Ireland is quite specific and very limited to the County Down coast.  It seems to require sheltered inlets like those at Dundrum, Strangford and Carlingford Lough.  We believe the larvae feed on the strand-line plants like Oraches. 

Brown beetle with yellow stripes on back

Cassida nobilis - AfroBrazilian

Northern Chafer - A Rarity in Ireland

Finally, my other favourite because of its rarity and impressive size is the northern chafer.  This beetle is very similar to the common cockchafer, but in Britain and Ireland it is only found on exposed coastal northern and western areas with light sandy soils. 

As light sandy soils are a rarity in Ireland, so is this beetle!  Until 2016 this beetle hadn’t been seen alive in Ireland for over 100 years, until I found it at White Park Bay. subsequently I also found it at Ballykinler Training Centre.  On both occasions it was captured at light traps set out to study moths.  For any moth trappers on the western and northern coasts of Ireland this is definitely one to look out for! 

Brown beetle on green leaf

Melolontha hippocastani, the northern chafer By Fritz Geller-Grimm

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Kingfisher (c) Tony Dalton