The Rothamsted Insect Survey: A national asset with a local history

Talk by Dr Richard Harrington to the Society on 29 January 2015

Report by Joyce Bunting

Photo:Dr Richard Harrington

Dr Richard Harrington

Rothamsted Insect Survey website

On 29th April 2014 Rothamsted Research in Harpenden celebrated 50 years from the founding of the Insect Survey. Dr. Richard Harrington, current Head of the Insect Survey Group at Rothamsted, outlined its history, value and future to the Society at a meeting in January 2015.

Suction traps

In 1962, Rachel Carson’s book ‘Silent Spring’ shocked the world with its findings on the effects of pesticide on wildlife. UK Government made money available to develop research, resulting in the first insect suction trap to be set up in 1964. By 1968 a UK network was established. 15 suction traps are currently in operation.

Photo:Suction Trap

Suction Trap

Rothamsted Insect Survey website

Flying insects are continuously collected in the suction traps, which work like a giant upside-down vacuum cleaner. Two traps can be seen at Rothamsted Research from the Lime Avenue going up towards Rothamsted Manor. They sit at the top of masts 12.2 metres (40 ft) tall. Collected insects are identified and counted, and the results recorded on the long-term data base held at Rothamsted. All these samples are dated and stored. They dry out somewhat over time, but remain identifiable as an important source for research.

Aphids are some of the most important insects identified. 600 species of aphids are found in the UK; about 50-60 species can damage food or forage crops. Weather conditions in January and February affect when aphids will strike in spring. Predictions can be very accurate, using previous data and current sightings. Results and warnings to farmers are issued every Friday via e-mail and web bulletins in ‘Aphid News’. This means agriculturalists can spray against aphids when they are actually present or expected, thus reducing the use of pesticides. Young plants are very susceptible to aphids until about June.

Some grain aphids are now resistant to Pyrethroid insecticides – the same insecticides which were developed at Rothamsted in the 1960’s and 70’s. This resistance can be detected via DNA in samples collected in the insect traps. Many aphids have a life cycle including frequent parthenogenesis (live young born without fertilisation) so mutated insecticide-resistant species can spread very quickly across the country.

Light traps

Photo:Light Trap

Light Trap

Rothamsted Insect Survey website

Ramblers around Rothamsted field paths will have noted the light traps. They stand in fields and hedgerows at chest height. A 200 watt tungsten electric bulb attracts insects, which fall into the receptacle below. 84 light traps are working today in various habitats.

The working parameters for the light traps haven’t changed since they were set up in 1960. All the collecting conditions must be the same year on year. However, electric bulbs have changed to low energy, which do not give quite the same light as the old tungsten bulbs. A large stock of 200 watt tungsten bulbs from abroad has been acquired, but what will happen when they run out?

Large moths collected in the light traps are identified, counted and recorded. This is done mostly by local volunteers, amongst whom are former employees and scientists from Rothamsted Research. Two-thirds of the larger moths have significantly declined in numbers over the last 50 years. Over a recent 4-5 year period, a decline of 30% amongst the larger moths has been noted, whilst other species have increased. Reasons for these changes are being sought, because large moths are an indicator of ecological health.


Climate change has led to an increase in pests and a decrease in beneficial insects. Insect pests are very mobile, highly fecund and therefore very adaptable, whilst predatory insects are specialised and need longer to adapt. They are not coping so well with climate change, so their effect on pests is lagging behind.

Radar tracking of migrating insects may prove useful in future, but at present only insects of house-fly size and above are detectable.
A new comprehensive data base is in process at Harpenden – so history is still in the making.

Fossilised aphid

Dr. Harrington, who is also vice-president of the Royal Entomological Society of London, won an auction on eBay for a piece of amber containing a fossil aphid. He sent it to Professor Ole Heie, an aphid expert in Denmark, who confirmed the insect as an unknown species, now extinct. The aphid has been named Mindarus harringtoni and now resides in the Natural History Musem. So there’s a bit of history from 40 to 50 million years ago!

Further notes adapted from The Rothamsted Insect Survey strikes gold. Harrington, R. (2014)  Antenna 38, 158-166.

The Rothamsted Insect Survey was born out of Professor L. R. (Roy) Taylor’s quest to understand how and why insects migrate. Insect migration is crucial to changes in their abundance in time and space (population dynamics). Data on the changes in insect abundance from a wide area, and mathematical analysis, were required to enable a good understanding of insect migration.

Understanding population dynamics leads to prediction of abundance and hence of the need for pest control.

Aphids and moths were chosen as they have contrasting life histories and pioneering work at Rothamsted by C.B. Williams, C.G. Johnson and Roy had led to the development of traps suitable for aphid and moth surveillance.

Funding for the establishment of the trap networks was provided by the Government in the early 1960s, partly as a result of Rachel Carson’s seminal book, Silent Spring, published in 1962.

The suction-trap at Rothamsted entered continuous operation on 29th April 1964 and other traps were soon introduced.

The light-trap on Barnfield, Rothamsted Estate, was first switched on in 1933 and ran for four years. It ran for a further four years from 1946 to 1950. In 1960 it started again and has run continuously ever since. In 1964 a nascent network was established with traps in Hatfield (Herts.), Stratfield Mortimer (Berks.) and Dale Fort (Pembs.) and by 1968, 60 traps were running nationally. To date traps have been operated at nearly 500 sites for at least a year.

The trap networks have been proven invaluable, as Roy predicted, in a very wide range of studies spanning the full spectrum of fundamental to applied ecology. Roy Taylor was born in 1924. He was appointed to the Rothamsted staff in 1948 and retired in 1984. He died in 2007. He was President of the British Ecological Society in 1984-1985.

This page was added by Rosemary Ross on 08/03/2015.

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