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It’s a bug’s life: why the eradication of an outbreak of termites in Devon is a big deal

Words:
Ed Suttie

While the UK does not provide optimum living conditions for termites, climate change and the increasing likelihood of the insects being accidentally imported makes it vital these risks are understood

Subterranean termites.
Subterranean termites. Credit: iStock

In September 2021 it was announced that an outbreak of subterranean termites in the UK had finally been destroyed, in what is believed to be the first time that the insects had been eradicated from a country.

The Steering Group of the UK Termite Eradication programme agreed that in all likelihood eradication had been successful, nearly thirty years after the termites were discovered in the UK.

Globally, termites are regarded as the most economically damaging urban pests given their potential to severely damage timber buildings. Conversely, in natural forest systems, grasslands and other natural ecosystems, especially in the tropics, they are regarded as ‘soil engineers’ vital to nutrient cycling, the maintenance of soil structure and ecosystem balance. Termites are predominantly tropical and subtropical in distribution. However, mainly as a result of human activity and warming climates, they are being found in increasingly more northern and southern latitudes. Subterranean termites are endemic in Southern Europe and in France where there is so-called ‘termite law’ regarding the construction of buildings to ensure they are protected against termites.

Devon termites

While termites are not endemic in the UK, subterranean termites (of the species Reticulitermes grassei) were found in a private property in Devon in 1994. They were subject to an intensive eradication and monitoring programme in 1998 after the termites were found present in large numbers and distributed across at least two properties. This remains the only known established infestation of subterranean termites recorded in the UK. Despite initial success in bringing about the collapse of the infestation, a localised reappearance of termites was recorded in 2009 and 2010, resulting in the eradication and monitoring programme being extended. The programme being managed by the Department for Levelling Up Housing and Communities and delivered by BRE ended in 2021, declaring that, in all likelihood, that eradication has been successful. This significant milestone is a great achievement and a global first.

However, in the face of the globalised transport of goods and climate change we must remain vigilant and aware that termites might still be brought into the UK. Part of the closing phase of the programme is to ensure a legacy of improved termite awareness within the construction and architectural communities. This will help provide a more rapid response should termites occur again in the UK.

What type of termites?

The economically important termite species (that can cause damage timber in buildings) are subterranean termites and drywood termites. There are a number of key distinctions.

Subterranean termites

Drywood termites

Require a continuous source of moisture

Rely on moisture content of dead wood

Concealed in earthen or mud workings

Produce ‘kick’ holes from which they expel poppy seed-like faecal pellets

Generally consume wood along the grain, preferring softer spring growth and often leaving intact wafers of timber comprised of harder summer growth

Generally consume wood across the grain, consuming both spring and summer growth

Often form large colonies or inter-connected colonies comprised of thousands or millions of worker termites

Colonies are often small, typically comprising less than 250 workers, although multiple colonies can exist in the same piece of wood

Termites are difficult to identify to species, normally requiring either the soldiers, each species with definititive head shapes and structures, or alates, with distinct wing structures and patterns of venation.

The three key signs of infestation include the presence of damaged timber, signs of live termites and evidence of termite workings. Timber might appear sound on the outside, but be hollow as result of termite activity inside. The damage may be checked by ‘sounding’, which involves tapping the timber with a solid object, such as the handle of a screwdriver.

  • Timber bait being removed for inspection from a supplementary monitoring device that goes 1m vertically into the ground.
    Timber bait being removed for inspection from a supplementary monitoring device that goes 1m vertically into the ground. Credit: BRE
  • Dr Rob Verkerk heading into the underfloor void of one of the houses to inspect the monitoring stations.
    Dr Rob Verkerk heading into the underfloor void of one of the houses to inspect the monitoring stations. Credit: BRE
  • A ‘poly-chain’ monitoring system developed for the underfloor void showing bait timber withdrawn for inspection.
    A ‘poly-chain’ monitoring system developed for the underfloor void showing bait timber withdrawn for inspection. Credit: BRE
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How could termites get to the UK?

There is a wide variety of ways in which termites could be brought into the UK, these almost certainly involving humans. The significance of importation is different for subterranean termites compared with drywood termites, the latter being of much lesser economic significance to buildings given that populations of drywood termites would be unable to survive outdoors in the UK and can be effectively treated locally indoors.

Subterranean termites can be imported on any cellulose-based material that has been brought in from an area where subterranean termites are established, such as susceptible timbers (particularly softwoods) including logs, stored timbers, crates and pallets.

Drywood termites are most likely to be imported from areas of endemic infestation, such as the southern states of the USA, the Carribbean, Africa or Asia, in timber items such as potted plants, furniture, musical instruments, chests and ornaments. 

Even if subterranean termites are not detected during border inspections, successful establishment requires optimal conditions, including lack of disturbance, preferably sandy soils, a source of moisture, appropriate temperatures and an adequate supply of cellulose-based food sources to sustain growing colonies. While the biogeographic range of R. flavipes in France, the nearest area of endemic infestation to the UK, continues to move northward and especially while infestations in Paris continue to expand, it is noteworthy that the South East of England, the part of the UK nearest to France with the highest frequency of transport between continental Europe and the UK, has predominantly loamy or clay loam soils. Such soils tend not to be as preferred, especially by the European indigenous species.  

The fact that only a single established infestation in the UK has ever been detected is also a reflection of the rarity of establishment of subterranean termites. However, the continued rise in human transportation and trade, the northward expansion of subterranean termites in Europe, along with warming climates, all conspire to increase the risk of importation of both subterranean and drywood termites. The threat of successful establishment of subterranean termites is increased where there are heat sources near or in the ground, such as underfloor heating systems in concrete slab-on-ground structures, especially those on which timber framing is present. 

Call to action    

Be vigilant over and look for termites. For more information and to report possible infestations visit the BRE website.

Ed Suttie is BRE Head of Consultancy

 

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