Jalmenus evagoras larvae and pupae are also known to produce several kinds of acoustic signals by stridulation (Hill 1993; Pierce et al. 2002). The pupae possess a file and plate stridulatory organ which is similar to pupal organs found in a number of other species (Downey 1966). A set of teeth on the anterior margin of the sixth abdominal segment (the file) is scraped against a series of ridges and depressions on the fifth abdominal segment (the plate). Travassos (1997) determined that the pupae produce two types of sounds, a primary and a secondary signal. The primary signals have a higher amplitude than secondary signals and sound like a distinct ‘chirp’. He noted that less well-developed sets of teeth are also found on the anterior portions of abdominal segments 5, 7 and 8, but in each case, these lacked an opposing plate. In larvae the structure is found between abdominal segments five and six and the relative positions of the file and plate is reversed (Hill 1993). It is thought that the noise produced may act as a deterrent to predators and parasites (Downey and Allyn 1973); however, Ross (1966) and DeVries (1992) suggest that the sounds produced by pupae are used to 'call' the ants. Travassos and Pierce (2000) conducted a simple experiment wherein they occluded sound production in half of a group of J. evagoras pupae and found that calling pupae attracted and maintained a significantly higher ant guard than their silent counterparts. Thus, it appears that acoustic signalling by lycaenids plays an important role in their symbiosis with ants.

Information sourced from:

Pierce, N. E. and Nash, D. R. 1999. The Imperial Blue, Jalmenus evagoras (Lycaenidae). In: Monographs on Australian Lepidoptera Volume 6. Biology of Australian Butterflies (eds. R. L. Kitching, E. Scheermeyer, R. E. Jones and N. E. Pierce) pp. 279-315. CSIRO, Melbourne.

References cited:

DeVries, P. J. 1992.  Singing caterpillars, ants and symbiosis.  Scientific American 267(4): 76-82.

Downey, J.C. 1966. Sound production in pupae of Lycaenidae. Journal of the Lepidopterists’ Society 20: 129-155.

Downey, J. C. and Allyn, A. C. 1973.  Butterfly ultrastructure: 1. Sound production and associated abdominal structures in pupae of Lycaenidae and Riodinidae.  Bulletin of the Allyn Museum of Entomology 14: 1-39.

Hill, C. J. 1993.  The myrmecophilous organs of the butterfly Arhopala madytus Fruhstorfer (Lepidoptera: Lycaenidae).  Journal of the Australian Entomological Society 32: 283-288.

Pierce, N. E., Braby, M. F., Heath, A., Lohman, D. L., Mathew, J., Rand, D. B. and Travassos, M. A. 2002.  The ecology and evolution of ant association in the Lycaenidae (Lepidoptera).  Annual Review of Entomology 47: 733-771.

Ross, G. N. 1966.  Life history studies on Mexican butterflies. IV.  The ecology and ethology of Anatole rossi, a myrmecophilous metalmark (Lepidoptera: Riodinidae).  Annals of the Entomological Society of America 59: 985-1004.

Travassos, M., 1997. Calling caterpillars, pulsing pupae: Vibratory communication in the Common Imperial Blue Butterfly, Jalmenus evagoras (Lepidoptera: Lycaenidae). Senior thesis, Harvard University.

Travassos, M. A. and Pierce, N. E. 2000.  Acoustics, context and function of vibrational signalling in a lycaenid butterfly-ant mutualism.  Animal Behavior 60: 13-26.