The wettest winter since records began could have damaged dragonfly and damselfly populations for years to come, according to The Canal and River Trust.
The Trust said fluctuating river levels and fast currents are known to wash away dragonfly larva (or nymphs).
As larva live underwater for up to three years, unprecedented floods may have a long-term effect on populations.
Now the Trust is asking people to help monitor the insects as part of its annual Great Nature Watch, which launches today.
Peter Birch of The Canal and River Trust, said: “Dragonflies, and their sister damselflies, flourish in clean water which is rich in bankside vegetation, such as reeds. This makes them a fantastic indicator of the health of a canal or river.
“While this year’s floods have had an obvious impact on larger animals, birds and fish, we are also particularly concerned with the impact on invertabrates, which form the foundation stones of a healthy water environment.
“We would expect to see an increase in numbers of mosquitoes and midges which prefer stagnant and isolated water, but we may also see a drop in the numbers of dragonflies emerging this spring.
“By taking part in the Great Nature Watch, you can help us monitor numbers of dragonflies, damselflies, and in fact, all species living on Lancashire’s canals and rivers over the coming years.”
For further information visit: www.canalrivertrust.org.uk/great-nature-watch.