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What Is a Darkling (Litter) Beetle?

Rowan Burgess |

Found throughout the natural world and spanning the entire globe, the darkling beetle is often seen as a pest to the agricultural industry, but the vast majority of species reside naturally in the wild. Yet while many consume bark, leaves, and other decaying matter far away from human activity, some species have a rather frustrating fondness for animal faeces, crops, and just about anything that can be found in a dark, cool farm building.   


The term “Darkling Beetle” can be misleading because it does not refer to a specific species but a staggeringly wide range of more than 20,000 species that fall under the Tenebrionidae family umbrella. And to complicate things further, they are also widely known as Litter Beetles, with different variations found across the world. Sound confusing? We'll explain.      

Lifecycle of a Darkling Beetle

The lifecycle of the darkling or litter beetle can cover anywhere between 30 and around 180 days, depending on external conditions - beginning with the eggs laid by full-grown beetles. Eggs hatch to produce larvae - or mealworms, as they're commonly referred to - in as quickly as four days or as long as two weeks. 

Mealworms remain in their larvae form for between 8 and 10 weeks, during which they continue to grow before eventually outgrowing their exoskeleton. Once shedded, they then move to their penultimate stage, known as Pupa. 

During this period, the litter beetle in waiting will curl slightly and take on a pale colour that can easily give the impression of death, but this is all part of the process. While they appear inactive or dormant during this time, a lot is happening on the inside. After between 1 and 3 weeks, the pupa splits open to reveal a beetle that emerges for its final life stage. 

Darkling beetles begin mating almost immediately and usually start laying eggs after 1 or 2 weeks. Their lifespan generally ranges anywhere from 3 months up to a year, during which they will constantly lay eggs - though theoretically, darkling beetles can live up to 20 years or more. No wonder getting rid of them can be so difficult!           

Darkling Beetle Identification

As mentioned above, the term “darkling beetles” encompasses many beetle species, which often vary in different parts of the world. In the UK, an adult darkling beetle can be anywhere from 2 mm to 4 cm in length, and it’s typically dark brown or solid black. Unable to fly, its wings are fused over its back, while two antennae attach close to the eyes.  

Darkling Beetle Living Habits

Litter beetles are nocturnal insects that thrive in dark, cool environments and can happily live under rocks or logs - but also in farm or poultry buildings. Interestingly, insulation material located in roofs is a favourite dwelling for beetles, and it's easy for their numbers to surge in these rarely seen areas. Now, onto impact.   

The Impact of Darkling Beetles

Litter beetles, though small, can have a dramatic impact in several ways, ranging from lowering overall flock performance to spreading deadly diseases. 

Flock Performance

On poultry farms, litter beetles can seriously affect flock performance, as young birds often choose to feed on beetles before moving on to their own food. What's the problem? The beetle shell is indigestible and can cause severe distress when defecating, leading to reduced efficiency and increased feed conversion. Both of these can have an enormous impact on large flocks.      

Biosecurity Impact

Litter beetles also host a nasty catalogue of diseases, such as Newcastle disease, avian influenza, Marek's disease, infectious bursal disease, Salmonella, and 26 pathogenic types of E. coli. Any one of these can decimate a flock, making those tiny beetles a serious biosecurity risk to a poultry farm.  

Economic Impact

The economic impact of litter beetles can be felt in two very different ways. Firstly, they can cause severe structural damage to buildings when burrowing into materials to pupate and dramatically reduce a structure's insulation. 

The second economic impact is their effect on other animals in the vicinity. An avian influenza outbreak caused by litter beetles can effectively destroy livelihoods, while the seriousness of being responsible for a salmonella or E.Coli outbreak can be equally catastrophic.  

Human Impact

Litter beetles do not bite humans or pose any direct threat, but the problems do stack up - indirectly. While it's relatively rare to find these types of beetles in homes, they are common in gardens, as well as on farms and silos. Any seasoned gardener will warn you of the damage darkling beetles can cause to young plants, while, as we've covered, their impact on farms can have risky health implications further down the road.   

Frequently Asked Questions

Are Darkling Beetles and Litter Beetles the Same?

Yes, darkling and litter beetles are the same. However, as mentioned, the name ‘darkling’ actually covers more than 20,000 different species of beetle, many of which live in the wild and are a perfectly normal part of the ecosystem.  

Are Darkling Beetles and Lesser Mealworms the Same?

Yes, but the two names refer to different stages of the beetle's life. After hatching, the beetle, still in its relatively primitive form, is known as a lesser mealworm. While in this form, mealworms are used as pet food, as well as fish bait and wild bird food.      

Are Darkling Beetles Harmful?

It depends on your definition. While darkling beetles don't cause direct harm to humans, their trickle-down effect can be substantial. Beetles can be particularly damaging to flocks of birds and poultry, as well as being disease superspreaders.  

Can Darkling Beetles Bite?

The good news after all that is that at least darkling beetles don't bite. They can certainly be a real pain to get rid of, but biting isn't something you need to worry about.  

Final Thoughts

As we've seen, the darkling beetle can seismically impact agriculture. Like many insects, their reproductive speed means that a problem left untreated can quickly spiral out of control, so it's important to nip it in the bud early. 

Dalton has been dealing with litter beetles for over 30 years - among many other pests. With our Alphi WG formula, you can strike at the heart of the problem. Alphi goes after both the adult beetles and the larvae, meaning you're attacking two separate fronts. It may take some time and effort, but with Dalton, that darkling beetle problem can quickly become a thing of the past.