Warwickshire Dragonfly Group


Observations of Willow Emerald Damselfly, Lestes viridis

Made by Kay and Peter Reeve

Visits were made to Alton Water and the River Deben, Suffolk on the three days 19th, 20th & 21st August 2011. Two visits were made to Alton Water (Grid ref. TM136377) on the afternoon of 19th August, 15.15 to 17.00 BST, and the morning of 20th August, 10.45 to 14.15 BST. The River Deben near Quill Farm, Campsea Ashe (Grid ref. TM315557) was visited on the afternoon of 21st August, 14.00 to 16.45 BST. Our observations made of the behaviour of Lestes viridis are detailed below. Those made at Alton Water are described in reversed day order so that they follow chronologically the hour of the day.

Alton Water

The weather was warm and sunny on both days during the periods observations were made. The temperature was 20°C rising a few degrees until early afternoon. The wind was about force 2 to 3. As noted above, the the observations are in reverse day order.

Willow Emerald - maleWe moved away from the car park (TM13653743) along the bank-side path in an easterly direction at 10.45 BST. Soon individual male and female L. viridis were seen in the herbage and on trees beside the path, approximately 20 metres from the water's edge. They were feeding on small flying insects in darter fashion; flying from their perch, catching the insect and returning to their perching place to consume the prey. None were at sites selected for breeding later in the day. In the next 45 minutes many individuals were seen away from the water, up to 100 to 200 metres, particularly in an area of grassland and trees (the area in the vicinity TM13313761), mainly fairly mature oak. As time progressed tandem pairs appeared though no copulation was observed in this area. As the water's edge was approached, more tandem pairs were seen but still away from suitable breeding sites. We arrived back at the water (TM13483764) at circa 11.30 BST and soon tandem pairs were seen arriving. After about ten minutes the first female, still in tandem with the male, was observed ovipositing into the bark of a Willow branch overhanging the water. More pairs were observed until about six pairs were in view, moving from oviposition site to oviposition site which were all on Willows. The branches selected for oviposition varied in diameter from circa 0.5 cm. to a maximum of circa 2cm. No males were observed holding territory until circa 12.30 BST. A slow return was made to the car park and, as time passed, more and more ovipositing pairs, males holding territory, and pairs copulating in the trees overhanging the water, were observed. Also, a few lone females were seen ovipositing. There were still good numbers away from the water feeding and basking in the sun both in the grassland/wooded area and in an area with many large live and dead umbellifers (mainly Wild Angelica Angelica sylvestris, grid ref. TM13483752). The non-breeding individuals were now closer to the water's edge than earlier in the day. We arrived back at the car park at circa 14.15 BST.

We left the car park at 15.15 BST following the roughly same route (this is on 19th August). Immediately male and female L. viridis were found perched, many on the live and dead umbellifers, and feeding within 1 to 5 metres of the water. Close to and at the water's edge there were males holding territory among the Willow branches between 1 to 3 metres above the water level and up to 1 or 2 metres away from the water. Tandem pairs were observed ovipositing from 1 to 5 metres above the water in the Willow branches and all those observed were over the water. There were a few individual females ovipositing. A few copulating pairs were also observed. Moving into the area of grassland and fairly mature trees (mainly oaks) about 100 to 200 metres from the water there were many individuals of both sexes evident perched in the trees and grass. The water's edge was reached again at circa 16.15 BST and many fewer L. viridis were seen holding territory or ovipositing than an hour earlier. A slow return was made to the car park. Where an abundance of individuals had been seen on umbellifers earlier in the afternoon there were now very few. Those present were more evident slightly further from the the water, 5 to 10 metres. By circa 17.00 BST none were to be seen at the water. The car park was reached at 17.30.

River Deben, Campsea Ash

A visit was made to the Deben between 14.00 BST and 16.45 BST, 21st August 2011. A length of river bank was covered from TM31515525 to TM31005581, out and return. The weather was dull but very warm, mid 20ºC, with occasional very short bright periods.

Willow emerald - femaleSearches along the first 200 metres of bank yielded sight of three individuals on foliage overhanging the river between 0.5-4 metres above the surface. More careful study of the overhanging trees, predominantly Willows, produced sightings of three further males and at 15.15 BST the first ovipositing tandem pair was found. The next 45 minutes yielded two more ovipositing pairs and a single female ovipositing. The last ovipositing pair were seen to separate at 16.00 BST. All the individuals and ovipositing pairs were on Willows between 1 metre and 8 metre above the water surface. Returning along the bank from 16.00 BST to 16.45 BST nine individuals were seen on Willows over the river, seven males, one female and a further unsexed individual. During the visit, in addition to those individuals over the river a number were observed in the bankside vegetation, four females and two males. It was noticeable that when disturbed these individuals flew up into the tree canopies. The river was left at 16.45BST.

Banner artwork by Joan Sharrett

Last updated Tue Aug 07 22:01:41 2012

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