A handful of insects emitting green, yellow and red light of exceptional strength was spotted in Stockholm, Sweden back in 1986. Once collected this colorful insect may give important insight into insect evolution and bioluminescence. Some observations were made at a close distance giving a clear picture of their action. A few snapshots show patterns of light resembling that of known species. Insects of this nature aren’t supposed to appear in Scandinavia, but unique beetles are sometimes found in old oaks which were more widespread in the past and back in the Stone Age.
The wide red light trail above shows two insects expanding their light, one of them after flashing green and yellow attracting the other (the latter with much weaker, fuzzy red light on film). There is also a thin trail of reddish light from an alone insect below following the others at a short distance. The sequence of expanding light above was repeated for several evenings, mostly as fast divings from high altitude making them easy to spot from a distant point overlooking a wider area over the treetops.
From exposure data (low sensitive Kodak Gold 100 ASA analogue film, f:2.8, approx 3 seconds) this new species is estimated to be the brightest light emitting insect on Earth. It is approx. ten times brighter, see ‘Calculus’ below, than the much similar Pyrophorus which also is expanding its light (a unique property of these two species only, hence a suggested relationship) and so far had got the light record.
A realistic Java-animation of one insect.
A close-up photo shows an insect that ligths up surrounded by weaker light reflected by the wings (short time exposure), after having been attacked by another insect (the thin red track at low left):
The insects´ habitat in the south of Stockholm:
A possible living-tree and ecological nisch, a ca 500 years old hollow oak situated on a hillside in this desolated forest area. It had a narrow opening and a cavity of 1x1.5 m width at its base, making glowing inside the tree at high daytime temperatures an option in this cold swampy area (the much similar species Pyrophorus has been observed in caves on Cuba). Unfortunatley this specific oak was removed for security reasons and never investigated:
SHOCKING STRENGTH OF LIGHT
According to expertise (see Expert’s comments below) photographing known emitters need at least 1 minute exposure time using 100 ASA film (at a large aperture), but in this case only a fraction of a second was needed. By making use of a method in astronomy and dividing a track of light on the film into equal segments, each one corresponding to the size of the object, the exposure time for that object can be derived and compared to known objects/species.
The photo shows a green flashing insect that changes to yellow and then into a continous, 2-3 cm wide red light after attracting another insect emitting a wide, diffuse red light, also visible on the film at that color change. Below those two insects there is a single insect emitting pale but still very strong red light of approx. 0.8 cm width, moving at constant speed during approx. 3 seconds.
This pale track of light can be divided into approx. 100 segments giving an exposure time of 3/100=0.03 seconds - to be compared to the 60 seconds needed for known species…
The exposure difference compared to known species then can be expressed in aperture stops on a camera by dividing the 60 seconds by 2 until one gets 0.03 seconds. Approx. 10 aperture stops differ, which any experienced photographer can verify is quit a lot:
60-30-15-7.5-3.75-1.88-0.94-0.47-0.23-0.12-0.06-0.03
That is physical evidence.
However, the flashing light and wide continous red light are significantly stronger than this pale red light track on film, and were quite shocking in vivo.
A 12O MILLION YEARS OLD RELATIVE
The possibility of spotting an immigrated insect that also happens to be new to science is small and could be ruled out.
Let p represent the probability of spotting an immigrated insect, let´s say 1 out of 1000 observations. Then let q represent the probability to find a species new to science amongst those observations, let´s try 1 out of 1.000.
The probability S of spotting an immigrated insect that also is new to science is then given by the ‘Multiplication rule’:
S = p * q = 1/1000 * 1/1.000 = 1/1000.000
A rough model, but it gives an idea of what one might expect. Increasing p and q doesn’t alter the significance of the small outcome of S.
A surprising implication is that the much similar but less powerful Pyrophorus, living in South and Central America, is likely to be an old relative from the time before the continents started drifting apart about 120 million years ago…
The new Swedish species might represent the most powerful firefly nature has ever created. All three colors - green, yellow and red appeared extremely bright and clean, as on the photo, with the red color at some occasions slowly adjusting itself into a colordepth that was breathtaking.
EXPERT´S COMMENTS
Universidade de São Paulo (16 Oct 1997):
"IN VIVO, we have never found any red emitting lampyrids (fireflies) no elaterids (click-beetles). In the literature, there is no report on red emitting lampyrid and elaterid either. The only red-emitting insects we know are some genera of phengodids (railroad worms) such as Euryopa and Phrixothrix.
IN VITRO, one can manage getting red light from lampyrids by lowering the pH. In the case of elaterids, Wood et al, Science 244, 700 (1989) were able to isolate a red-eliciting luciferase from the elaterid Pyrophorus plagiophthalamus.
Light emission from known insects is not so intense that it can be photographed without a long exposure (>1 min, 100 ASA film). You have a very intriguing case in hands."
Smithsonian Institution (13 Apr 1998):
"There are several families of beetles that emit light in flight as you describe [with exception of red light]. The most common are fireflies (beetles, family Lampyridae). Lampyrids usually produce small dots or short streak-like flashes; however, in the click beetle family there is a group of large light-emitting species named Pyrophorus = fire bearing.
The light-emitting click beetles occur in fair numbers in tropical areas of Mexico, Central America, and South America and they resemble pen-lights flying from tree to tree."
The Johns Hopkins University, Baltimore (28 Dec 2001):
You have made a fascinating discovery. If you can capture even one of these insects and it is possible to verify that different light organs are the sources of the different colors it would be unique in firefly annals.
LITTERATURE
One in vivo report found on a red emitting click-beetle:
Heward, R. (1840). Memorandum on the fireflies of Jamaica, Entomologist, 1, 42-43. Talks of an elaterid with palish green lights on the thorax and a pale red light from the intervals between the rings of the abdomen (not observed in flight, however, and only if the insect was stressed).
In vitro reports on red light related to fireflies and click-beetles:
‘Bioluminescence and Chemiluminescence, Fundamental and applied aspects’. Wiley & Sons 1994. A few reports included.
Viviani & Bechara, Photochemistry and Photobiology 62, 490 (1995).
Colepicolo and Bechara, Insect Biochemistry 16, 803 (1986).
Wood et al, Science 244, 700 (1989).
Related:
‘Bioluminescent communication in insects’, J. E. Lloyd, review paper 1971, Annu. Rev. Entomol. 16:97-122.
Insect bioluminescence, pp.241-272. Lloyd, J. E. 1978. In P. J. Herring; [ed.], Bioluminescence in action. Academic, London.
Harvey , E. N. and K. P. Stevens. 1928. The brightness of the light of the West Indian elaterid beetle, pyrophorus. J. Gen. Physiol. 12: 269-272.
Nicol, J. A. C. 1978. Bioluminescence and vision, pp. 367-398. In P. J. Herring; [ed.], Bioluminescence in action. Academic, London.
Seliger, H. H. and W. D. McElroy. 1965. Light: physical and biological action. Academic, New York.
Bilden visar en eldfluga i flykten som lyser upp med ett 2,5-3 cm brett rött ljus. Det något svagare ljuset som reflekteras i vingparet och omger insekten kan urskiljas och bidrar till det tekniska bevisvärdet (kort exponeringstid, f:2.8, Kodak 100 ASA analog film). Kända eldflugor lyser för svagt för att kunna fotograferas i flykten, se expertkommentar från universitetet São Paulo på insekternas infosida. Detta är världens enda observerade rödlysande eldfluga, dock finns en äppelmask i Sydamerika som lyser med rött förutom grönt och gult ljus (Phengodidae: Euryopa, Phrixothrix), men betydligt svagare. Därtill finns havsorganismer som lyser med rött ljus.
