Glow worms triple numbers in Cotswold Water Park

Glow worms are actually beetles. Photo credit Dave Kilbey.

September 2011. This summer in the Cotswold Water Park saw a dramatic increase in reports of strange green lights on warm July nights, causing great excitement and delight to those who managed to catch a glimpse.

300% increase
The lights were actually the faint green glow emitted by the elusive glow worm, and following surveys carried out by the Cotswold Water Park Trust over the summer it appears there is a large increase in numbers compared with 2010, with more than three times the amount of glowing females recorded in 2011. Almost one hundred glow worms were recorded by night time surveys along the old railway line running from Cricklade to South Cerney (a nature reserve managed by the CWP Trust) and the canal tow path from South Cerney to Cerney Wick.

Beetles not worms
Glow worms are not ‘worms' at all, but they are in fact beetles, or more precisely ‘female larviform beetles'. These flightless females show off their bioluminescent rear ends to attract the flying males. Once they have successfully mated, the female's light goes out, she lays her eggs, and then she dies. The ultimate sacrifice for the continuation of her species' survival.

Habitat loss
Many factors are having a negative impact on the population of glow worms all across the UK, including the loss of habitat. Areas that were previously strongholds for glow worms have now been developed, and lights from nearby buildings can also provide false attraction for males on the lookout for a glowing mate. Changes in land management regimes such as grazing patterns or pesticide/herbicide use may also be altering conditions for glow worms themselves, or for their food source.

But here in the Cotswold Water Park, concerted efforts have been taken to halt the decline by adapting existing nature reserve management techniques to suit this ethereal creature.

"It's fantastic to see that for some wildlife, such as the glow worm, the smallest of alterations to basic management can have a huge positive impact. Holding back on the mowing of grass verges during the mating season allows the females to shelter at ground level during the day before climbing the stems at night to display their wares. Staff and volunteers here at the Cotswold Water Park Trust will keep working hard for the glow worm, as well as the continued enhancement of habitat for a diverse range of wildlife species" said Ben Welbourn, Biodiversity Field Officer for the Cotswold Water Park Trust.

Glow worms have increased threefold at Cotswold Water Park - Photo by Dave Kilbey

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