Tag Archives: moths

Entomological classics – the Light Trap

I think that even those of us who are not entomologists are familiar with the attraction that insects, particularly moths, have for light. The great Sufi philosopher Bahauddin Valad (1152-1231) wrote the following lines

a candle has been lit

inside me,

for which

the sun

is a moth.


In Shakespeare’s The Merchant of Venice (1596), Portia famously declaims “Thus hath the candle singed the moath.”

Moths and flame

It may thus come as a bit of surprise to realise that ‘modern’ entomologists were quite slow to develop bespoke traps that took advantage of this aspect of insect behaviour. That said, according to Beavis (1995) the Roman author Columella (Lucius Junius Moderatus, 4-7 AD), describes a light trap to be used to protect bee hives from wax moth attacks. A pretty much identical trap was still being used in 1565 (Gardiner, 1995) although he erroneously calls it the first light-trap. As far as I can tell the early ‘modern’ Lepidopterists used the white sheet technique, still used today, where a light source such as a paraffin lamp (nowadays an electric light or powerful torch) was suspended above or behind a white sheet, from which the intrepid entomologist collected specimens of interest that come to rest on the sheet. This can be very efficient but does require the entomologist to be ‘on duty’ throughout the trapping

White sheet

The white sheet technique.

period, although on a fine night, with good companionship and an ample supply of beer, or other alcoholic beverage, it can be a very pleasant way to spend a long evening 😉

The earliest published reference to a modern bespoke light trap that I have been able to find is a patent from 1847 for a modified beehive which includes a light trap to lure wax moths away from the main part of the hive (Oliver Reynolds, 184, US Patent5211; http://www.google.com/patents/US5211).

Reynolds beehive 3

The modified Reynolds Beehive incorporating moth trap.

The second published reference to a bespoke light trap is again one designed to control wax moths and is described in a patent application by J M Heard dated 1860. In this case as far as I can make out the lamp is actually glass coated with a phosphorescent material rather than using a candle or oil flame.

Figure 4

“The basin A, is supplied with a requisite quantity of molasses or other suitable substance to serve as a bait, and the inner sides of the glass plates c, of the lamp C, are covered with a mixture of phosphorus and oil or phosphorus combined with any suitable substance to form a cement, or a stick E, may be coated with the cement, said stick being passed through the tube e, into the lamp, as shown plainly in Fig. 1. The insects decoyed by the light and attracted by the bait, strike against the inclined glass plates c, and fall into the basin A. By having the plates c, inclined the insects are made to fall through the opening b, into the basin and said opening is permitted to be comparatively small and the cover a, of the basin in connection with the cover D, of lamp protect perfectly the bait from sun and rain, thereby protecting an unnecessary waste of the same. During the day the phosphorus of course is not needed unless it be cloudy, but the device is chiefly efficacious at night as the visits of the insects are mostly nocturnal.”

So whilst beekeepers and agriculturalists were busy using traps to attract moths to kill them what were the lepidopterists doing? It appears that they were using whole rooms as light traps as described here by H T Stainton in 1848.

Figure 5


A later Victorian entomological ‘how to’ book, added instructions of how to use gas and paraffin lamps outside, with the lepidopterist standing ready with his net (Greene, 1880).

The 20th Century was however, when we see the birth of the light traps as we know them today. First on the scene was the Rothamsted Trap, developed by the great C B Williams, which was


Rothamsted electric 6

The electric ‘fixed’ Rothamsted Trap.

Rothamsted portable 7

The ‘portable’ Rothamsted Trap – Williams (1948)

developed from earlier versions that he used in the 1920s and 1930s, in Egypt and England (Williams, 1924, 1935).

Rothamsted colour 8

Rothamsted trap in action


Apparently the first electrical light trap to use an ultra-violet light was made in 1938 (Barratt, 1989) and used in the 1940s (Fry & Waring, 2001) but it was not until 1950 that the first commercially available version was produced (Robinson & Robinson, 1950).

Robinson 9

The Robinson Trap – very popular and ideal for use in gardens where there is easy access to a mains supply.


Strangely, considering that the Americans had been first on the scene with patented light traps it was not until 1957 that the Pennsylvanian and Texas traps appeared on the scene (Frost, 1957) closely followed by the Texas traps (Hollingsworth et al., 1963). These traps used fluorescent tubes instead of bulbs and were particularly good at catching beetles, moths and ants. The Texas trap and the Pennsylvania trap were essentially the same, the main difference being that the Pennsylvania trap has a circular roof to prevent train entering the killing bottle. As Southwood (1966) somewhat tongue in cheek says, this may reflect the differences in the climate of the two states 😉

Pennyslvania 10

The Pennsylvanian Light Trap.

In the 1960s the Heath Trap appeared on the scene (Heath, 1965). This was billed as being extremely portable, being able to be carried in a back pack and also able to be run either from a mains supply or from a 12 volt battery.

Heath 11

The Heath Light trap.

Less expensive and more portable is the Skinner trap, (designed by Bernard Skinner in as far as I can make out in the early 1980s, please let me know if you know exactly) which comes in wooden and aluminium versions and is collapsible, so that if needed, several can be transported at once. It comes in both mains and battery versions.

Skinner elctric 12   Skinner portable 13

The Skinner light trap – relatively inexpensive and very portable.

An interesting combination of light and odour being used to attract and trap insects, in this case to ‘control’ them, is the Strube Stink bug trap. This is an American invention and is used to protect US householders against the the Brown Marmorated Stink Bug, Halyomorpha halys, an invasive species from Asia which appears to have developed a propensity to overwinter in people’s houses. I remember a few years ago that we in the UK were warned that it might cross the channel from France; this resulted in lurid headlines in the ‘Red Top’ newspapers with wording like ‘stench spraying insect’ being used 😉

Straub 14

Strube Stink Bug Trap


This appears to be a very effective trap; all the reviews I have read praise it highly, so if the Brown Marmorated Stink Bug does make it to the UK, the Strube trap will be the one to buy!



Frost, S.W. (1957) The Pennsylvanian light trap. Journal of Economic Entomology, 50, 287-292.

Fry, R. & Waring, P. (2001) A Guide to Moth Traps and their Use. Amateur Entomologist, Orpington, Kent.

Gardiner, B.O.C. (1995) The very first light-trap, 1565? Entomologist’s Record and Journal of Variation, 107, 45-46

Greene, J. (1880) The Insect Hunter’s Companion. W. Swan Sonnenschein & Allen, London.

Heath, J. (1965) A genuinely portable MV light trap. Entomologist’s Record and Journal of Variation, 77, 236-238.

Hollingsworth, J.P., Hartstock, J.G. & Stanley, J.M. (1963) Electrical insect traps for survey purposes. U.S.D.A. Agricultural Research Service 42-3-1, 10 pp.

Robinson, H.S. & Robinson, P.J.M. (1950) Some notes on the observed behaviour of Lepidoptera in the vicinity of light sources together with a description of a light trap designed to take entomological samples. Entomologist’s Gazette, 1, 3-20

Southwood, T.R.E. (1966) Ecological Methods. Chapman & Hall, London

Stainton, H.T. (1848) On the method of attracting Lepidoptera by light. The Zoologist, 6, 2030-2031

Williams, C.B. (1924) An improved light trap for insects. Bulletin of Entomological Research, 15, 57-60.

Williams, C.B. (1935) The times of activity of certain nocturnal insects, chiefly Lepidoptera, as indicate by a light-trap. Transactions of the Royal Entomological Society of London B, 83, 523-555.

Williams, C.B. (1948) The Rothamsted light trap.   Proceedings of the Royal Entomological Society of London A, 23, 80-85.


Post script

There are of course more light traps out there, many being variations of those described above, or for specific insect groups such as mosquitoes or aquatic traps for Cladocera (water fleas). Many ‘home made’ traps also exist, such as the ‘portable’ one I made for use on the field course that I used to run at Silwood Park.

Leather 15

The Leather Light Trap

I used a rechargeable battery lantern, but other light sources would also work. In retrospect I should have painted the Perspex black so that only the ‘entrance’ funnels emitted light. There was a tendency for insects to sit on the outside of the trap rather than enter it.

A useful link for those wishing to make their own traps can be found here http://www.theskepticalmoth.com/techniques/light-traps/ and Fry & Waring (2001) also has some very useful hints and tips.




Filed under Entomological classics, EntoNotes

Where have all the woolly bears gone? Woolly bears what are they?

Just a brief thought this week, mainly about shifting baselines and changing perceptions.  I attended the launch of the State of Britain’s Larger Moth’s Report   http://www.mothscount.org/uploads/State%20of%20Britain’s%20Larger%20Moths%202013%20report.pdf last week (February 1st) which as well as giving me the chance to catch up with a number of old friends, also enabled me to hear Chris Packham http://www.chrispackham.co.uk/  giving a lively and very entertaining talk about why moths are important and how he got hooked by ‘natural history’.  He cited as one of the main factors,  his childhood experiences of rearing (or attempting to rear) woolly bear caterpillars, the larvae of the Garden Tiger moth Arctia caja,  a widespread and common species when I was a child and teenager in the 1960s and early 1970s.

Woolly bear larva



When I was earning extra money working as a postman in the Vale of York during my student years, it was one of the insects that I could guarantee I would encounter on my round.   Despite its wide range and great abundance, this moth has suffered a huge decline in numbers and I have hardly seen one since I was a long-haired, flares wearing student.  Like Chris Packham, it was the opportunity to interact with such a striking insect, which kept me interested in the natural world despite the competing interests of girls and beer.  As I write, I am teaching on a module (Ecological Entomology) of our MSc Entomology course http://www.harper-adams.ac.uk/postgraduate/201004/entomology (incidentally the only one in the UK).  Having been reminded of the Garden Tiger by Chris Packham, I quickly substituted my population simulation modelling exercise on the Speckled Wood Butterfly, with one on the Garden Tiger.  After I had finished introducing the subject to the students, Kevin, a mature student said that it was collecting and rearing woolly bear caterpillars as a child that had led to him to be sitting in front of me now.  One of the other students, a recent graduate, piped up and asked “what is a woolly bear?  I have never heard of them”.   He was there because he had been inspired by his project supervisor.

I guess the point that I am trying to make, is that whilst Kevin and I were inspired to become entomologists by our childhood experiences, Craig had to wait until he was exposed to the wonder and awe of working with insects as an undergraduate.  So what’s the problem you may ask?  Both students have ended up in my class. There is a problem however; the last BSc in Entomology in the UK stopped running in 1995, there are no Entomology Departments in UK universities , there are as far as I can ascertain, very few academic entomologists who describe themselves as entomologists in their job title e.g. as Professor of Entomology.  As far as I know, there is only me, http://www.harper-adams.ac.uk/staff/profile.cfm?id=201220 and then there is Francis Ratnieks at Sussex who proudly describes himself as the UK’s only Professor of Apiculture http://www.sussex.ac.uk/profiles/128567.  Others who I regard as mainstream entomologists are not described as such as in their job titles, e.g. Richard Wall at Bristol, Professor of Zoology; Jane Memmott also at Bristol,  Professor of Ecology; Bill Hughes at Sussex , Professor of Evolutionary Biology; Charles Godfray at Oxford (Hope Professor of Zoology) and the list goes on.  Even Mike Siva-Jothy who describes himself as an angry old entomologist on Twitter is just listed as Professor. Unlike arachnologists in Canada who are extremely rare organisms as outlined in Chris Buddles’ great blog article http://arthropodecology.com/2013/02/06/where-are-all-the-arachnologists-and-why-you-should-care/  we are still around in fairly respectable numbers.  We do, however, seem to be making it difficult for potential students to find and identify us.  The reasons for why I think this has happened will be the subject of another blog.  The point is, that if we are hard to find and identify, then the pool of potential future entomologists is going to become smaller as fewer and fewer undergraduates are exposed to basic entomological teaching and thus fewer and fewer entomologists will make it through to academia and our profile will become even lower and therefore even fewer students will be able to be inspired and so on and so on.  As a result, we too are likely to become as endangered as Canadian arachnologists.

So, if you are an academic who works mainly with insects and you are able to identify more species than just those you work on, then why not identify yourself in your job title as an entomologist and stand tall and proud and countable.


Filed under Bugbears, Teaching matters, The Bloggy Blog