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Tiger beetle colours

I was taking photographs of some beetle specimens to use in my thesis defense to illustrate some of the species I collected in my research. Since I had the lights set up, and my personal insect collection there with me, I decided to see if I could capture some of the colours and shapes, etc. of various beetles that I find appealing. Here's one example; the iridescent venter of tiger beetles.

Enjoy Smile

6 blog comments below

That's a quality pic Ankhanu, cheers for sharing it here Cool
I love the macro perspective, you can see so much intricate beauty in the creepy crawly world. [/nursery school descriptive term]

Any reason for this ones particular iridescence? Is it a mating thing like "I'm sexy as", a defensive "Don't mess coz I'm hard as nails", or maybe just "Don't eat me because I taste horrible and you will die"

Love the hair (?) patterns on it's legs...and those jaws Shocked
watersoul on Tue Dec 13, 2011 12:46 am
Thanks, Watersoul… and thanks for pushing me. I've not known why tiger beetles (many of them at least) are iridescent underneath, though I've wondered. Your question pushed me to actually look into it Razz
Acorn, J.H. 1988. Mimetic tiger beetles and the puzzle of cicindelid coloration (Coloepter: Cicindelidae). The Coloepterists Bulletin 42: 28-33. wrote:
Iridescent colors are disruptive in the sense that it is difficult for predators to visually judge the distance between themselves and iridescent beetles, since both color and brightness change rapidly with viewing angle. The physics of this phenom- enon, where iridescence is produced by plane diffraction gratings, are outlined by Hinton and Gibbs (1971). Although iridescence in tiger beetles is produced by interference reflectors rather than diffraction gratings (Schultz and Rankin 1985), Schultz (1986) also interprets iridescence as a means to hinder visual tracking by predators, especially of rapidly moving beetles. In other iridescent beetles, however, bright colors can also be aposematic (Hinton and Gibbs 1971), and I argue here that some tiger beetles are as well.

I have a PDF of the paper if you'd like to read the whole thing.
Seago, A.E., Brady, P., Vigneron, J.-P. and Schultz, T.D. 2009. Gold bugs and beyond: a review of iridescence and structural color mechanisms in beetles (Coleoptera). Journal of the Royal Society Interface 6: S165-S184. wrote:
6.1.3 Aposematic (warning) colours
Although tiger beetles are, as all carabids, chemically defended to some extent, they have also evolved a remarkable diversity of defensive coloration mechanisms from the same presumably ancestral interference colours. Multilayer reflectors are used in aposematic colour signalling in some cicindelines (Shelly & Pearson 1978; Pearson 1985). Acorn (1988) reported that multilayer colours in some tiger beetles are used in the mimicry of sympatric, chemically defended blister beetles (Meloidae) and velvet wasps (Mutillidae). Vogler & Kelley (1998) analysed cicindeline colour pattern evolution in a phylogenetic context, concluding that bright colours in Cicindela appear to have two functions: either as an aposematic cue in strongly chemically defended beetles (subgenus Cicindelidia) or as a cryptics or disorientation colour in brightly iridescent but weakly defended species (e.g. C. sexguttata). Iridescence may serve to deceive visual predators when tiger beetles that appear bright in the Sun fly into shade and the colours are extinguished (Knisley & Schultz 1997; Schultz 2001).

Full article here:

Looks like it's a combination of camouflage and visual confusion and an advertisement that they taste bad.
Ankhanu on Tue Dec 13, 2011 1:35 am
Thanks for the informative answer and interesting link Ankhanu, I'd be interested in that pdf you mentioned as well, cheers.
...although I'm still kicking myself that I hadn't considered the camouflage option, doh!

This is a completely new interest topic for me so I'm gonna have to read a bit more as an idea has just popped into my head regarding similar iridescence in birds feathers, and the possible camo advantages for them while hunting insects.

Hmm, back to reading a bit more, I'm quite intrigued Smile
watersoul on Wed Dec 14, 2011 12:58 am

If you're wanting to do some searches on tiger beetles specifically, their group name is Cicindelinae, a sub-family of ground beetles (Carabidae). It's a relatively recent move to being a subfamily, and they were a proper family, Cicindelidae before that.

That's an interesting question regarding bird iridescence... but, I think it tends to be intraspecific display more often in birds than visual confusion/camouflage. If you find otherwise, do let me know Smile
Ankhanu on Wed Dec 14, 2011 1:21 am
Here's the setup I'm using to take my photos:

Basically a Schmitt box on a box, with some hot lights I bought for my wife's Christmas gift last year, a reflector to capture some of the lost light and bounce the strobe off, and my Nikon D80 with a poor-man's macro lens (reversed 50mm) and SB-800 speed light. I climb in between the umbrellas and lean in for the shot Razz
Ankhanu on Wed Dec 14, 2011 11:00 pm
Thanks for the close-up photo and interesting link, Ankhanu. That is still just buggy though. laugh
standready on Wed Dec 14, 2011 11:12 pm

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