Abstract: Olga B. Biryukova Olga B. Biryukova, Institute of Systematics & Ecology of Animals, Siberian Branch, Russian Academy of Sciences, Sb Ras, Frunze ul. 11, Novosibirsk, 630091, Russia. E-mail: olya-bir@mail.ru Myrmecol. News 10: 101 Ants have been considered so far to maintain mutualistic inter-relations with insects of three orders: Homoptera, Lepidoptera and Heteroptera. Mutualistic relations of ants with the sawfly larvae of Blasticotoma filiceti Klug, 1834 (Hymenoptera: Blasticotomidae) were recently discovered in the Altai Republic (Biryukova & al. 2006) and Moscow Region (Shcherbakov 2006). The study was conducted in coniferous forests in North-Eastern Altai (North terminal Teletskoe Lake) in September 2005 and from June to September 2006. Blasticotomidae larvae inhabit the inside of fern fronds (Athyrium filix-femina (L.) Roth, 1799) and are likely to feed on plant sap. The larva makes a hole in a frond to breathe and to excrete. Sawfly larvae have been found to have three types of secretions:…