Billen, J. P. J.; Brandão, C. R. F.; Paiva, R. V. S. 1995. Morphology and ultrastructure of the pygidial gland of the ant Dinoponera australis (Hymenoptera, Formicidae). Papeis Avulsos de Zoologia (São Paulo) 39 (9):209-216. PDF

Schoeters, E.; Billen, J. P. J. 1995. Morphology and ultrastructure of the convoluted gland in the ant Dinoponera australis (Hymenoptera: Formicidae). International Journal of Insect Morphology and Embryology 24:323-332.

Soroker, V.; Hefetz, A.; Cojocaru, M.; Billen, J.; Franke, S.; Francke, W. 1995. Structural and chemical ontogeny of the postpharyngeal gland in the desert ant Cataglyphis niger. Physiological Entomology 20:323-329.

Gobin, B.; Billen, J. P. J. 1996. Trail following in army ants (Hymenoptera, Formicidae). Netherlands Journal of Zoology 46:272-280.

Nascimento, R. R. do; Schoeters, E.; Morgan, E. D.; Billen, J.; Stradling, D. J. 1996. Chemistry of metapleural gland secretions of three attine ants, Atta sexdens rubropilosa, Atta cephalotes, and Acromyrmex octospinosus (Hymenoptera: Formicidae). Journal of Chemical Ecology 22:987-1000.

Wenseleers, T.; Schoeters, E.; Billen, J.; Hefetz, A. 1996. Morphologie et ultrastructure de la glande cloacale chez Cataglyphis niger. Actes des Colloques Insectes Sociaux 10:189-194.

Schoeters, E.; Billen, J. P. J. 1996a. The post-pharyngeal gland in Dinoponera ants (Hymenoptera: Formicidae): unusual morphology and changes during the secretory process. International Journal of Insect Morphology and Embryology 25:443-447.

Schoeters, E.; Billen, J. P. J. 1996b. The control apparatus of the venom gland in formicinae ants (Hymenoptera: Formicidae). Netherlands Journal of Zoology 46:281-289.

Billen, J. P. J. 1997a. In memoriam. Jozef K.A. van Boven (1915-1997). Belgian Journal of Zoology 127:105-106.

Billen, J. P. J. 1997b. Morphology and ultrastructure of the metatibial gland in the army ant Dorylus molestus (Hymenoptera, Formicidae). Belgian Journal of Zoology 127:159-166.

Billen, J. P. J. 1998. Exocrine glands in the legs of ants. [Abstract.]. P. 64 in: Schwarz, M. P.; Hogendoorn, K. (eds.) 1998. Social insects at the turn of the millennium. Proceedings of the XIII International Congress of IUSSI. Adelaide, Australia. 29 December 1998 - 3 January 1999. Adelaide: XIII Congress of IUSSI, 535 pp.

Ito, F.; Billen, J. P. J. 1998. Larval hemolymph feeding and oophagy: behavior of queens and workers in the primitive ponerine ant Prionopelta kraepelini (Hymenoptera, Formicidae). Belgian Journal of Zoology 128:201-209.

Morgan, E. D.; Billen, J. P. J. 1998. Pheromone communication in social insects: sources and secretions. Pp. 3-33 in: Vander Meer, R. K.; Breed, M. D.; Espelie, K. E.; Winston, M. L. (eds.) 1998. Pheromone communication in social insects. Ants, wasps, bees, and termites. Boulder: Westview Press, x + 368 pp.

Gotwald, W. H., Jr.; Billen, J. P. J. 1998. In memoriam Jozef K.A. van Boven (1915-1997). Sociobiology 31:143-145.

Peeters, C.; Ito, F.; Gobin, B.; Fannes, W.; Billen, J. 1998. Queen-worker divergence in the spermathecae of ponerine and myrmeciine ants. [Abstract.]. P. 369 in: Schwarz, M. P.; Hogendoorn, K. (eds.) 1998. Social insects at the turn of the millennium. Proceedings of the XIII International Congress of IUSSI. Adelaide, Australia. 29 December 1998 - 3 January 1999. Adelaide: XIII Congress of IUSSI, 535 pp.

Wenseleers, T.; Schoeters, E.; Billen, J.; Wehner, R. 1998. Distribution and comparative morphology of the cloacal gland in ants (Hymenoptera: Formicidae). International Journal of Insect Morphology and Embryology 27:121-128.

Wenseleers, T.; Ito, F.; Van Borm, S.; Huybrechts, R.; Volckaert, F.; Billen, J. 1998. Widespread occurrence of the micro-organism Wolbachia in ants. Proceedings of the Royal Society of London. Series B, Biological Sciences 265:1447-1452. PDF

Billen, J.; Ito, F.; Maile, R.; Morgan, E. D. 1998. The mandibular gland, probably the source of the alarm substance in Leptanilla sp. (Hymenoptera, Formicidae). Naturwissenschaften 85:596-597.

Gobin, B.; Peeters, C.; Billen, J. 1998. Production of trophic eggs by virgin workers in the ponerine ant Gnamptogenys menadensis. Physiological Entomology 23:329-336. PDF

Schoeters, E.; Billen, J. P. J. 1999. Les organes neurohemaux perisympathiques des fourmis et differences entre les castes femelles. Actes des Colloques Insectes Sociaux 12:139-142. PDF

Schoeters, E.; Ito, F.; Miyata, H.; Billen, J. P. J. 1999. Aberrant venom glands in Amblyoponini (Formicidae, Ponerinae): morphology, ultrastructure and histochemistry. Acta Zoologica (Stockholm) 80:3-9.

Billen, J.; Gobin, B.; Ito, F. 1999. Fine structure of the postpygidial gland in Aenictus army ants. Acta Zoologica (Stockholm) 80:307-310.

Gobin, B.; Billen, J.; Peeters, C. 1999. Policing behaviour towards virgin egg layers in a polygynous ponerine ant. Animal Behavior 58(5):1117-1122. https://doi.org/10.1006/anbe.1999.1245 PDF

Billen, J. P. J. 2000. A novel exocrine gland in the antennal scape of the army ant Eciton burchelli. Belgian Journal of Zoology 130:159-160.

Buschinger, A.; Billen, J. P. J. 2000. Morphology and ultrastructure of a specialized bacterial pouch in the digestive tract of Tetraponera ants (Formicidae, Pseudomyrmecinae). Arthropod Structure and Development 29:259-266. PDF

Billen, J. P. J. 2000. Novel exocrine glands in the hindleg tarsi of the ant Nothomyrmecia macrops. Australian Journal of Zoology 48:661-667.

Billen, J. P. J. 2000. Femoral and tibial glands in the ant genus Strumigenys (Hymenoptera, Formicidae). Belgian Journal of Zoology 130:111-115.

Billen, J.; Ito, F.; Tsuji, K.; Schoeters, E.; Maile, R.; Morgan, E. D. 2000. Structure and chemistry of the Dufour gland in Pristomyrmex ants (Hymenoptera, Formicidae). Acta Zoologica (Stockholm) 81:159-166.

Billen, J. P. J.; Grasso, D. A.; Mori, A.; Le Moli, F. 2001. Structural and functional changes of the Dufour gland in gynes of the amazon ant Polyergus rufescens (Hymenoptera, Formicidae). Zoomorphology (Berlin) 121:55-61.

Gobin, B.; Rüppell, O.; Hartmann, A.; Jungnickel, H.; Morgan, E. D.; Billen, J. 2001. A new type of exocrine gland and its function in mass recruitment in the ant Cylindromyrmex whymperi (Formicidae, Cerapachyinae). Naturwissenschaften 88:395-399.