Archaeological excavation of a settlement of the Olsztyn Group at Tumiany, distr. Olsztyn, in NE Poland (Fig. 1), led to the discovery of a stray find of a copper alloy brooch with a caterpillar bow, a form which in literature may be known better as Raupenfibel (Fig. 2). The specimen from Tumiany has a roughly lozenge-shaped plate on its head and a lozenge-shaped foot, details which classify it as variant 1b of II series (M. Tuszyńska 1988) and as ‘Wielbark’ design (A. Kokowski 1995). Caterpillar brooches are first documented during phase C2/C3–D but presumably most of them belong in phase C3–D. The map of their distribution indicates concentrations in the Kaliningrad exclave (Samland Peninsula), Poland (lower Vistula River, northern Mazowsze and Podlasie, Mazury and Suwałki area), Germany (Mecklenburg, on the Lower Elbe River) and West Slovakia. Isolated finds are known from the Baltic islands of Bornholm, Öland and Gotland, as well as from western Mazowsze and Lublin Region in Poland. Recovered from a settlement of the Olsztyn Group from the Late Migration Period the brooch of interest is more likely to be associated with the Wielbark Culture. This is indicated by the generally accepted dating of brooch forms with a caterpillar bow, decidedly earlier than the time of crystallisation of the Olsztyn Group. Even more importantly – all analogies to the find from Tumiany occurred in Wielbark cemeteries found in the region on the lower Vistula River to the west (Pruszcz Gdański, Węgrowo, Malbork-Wielbark) and northern Mazowsze to the east (Kozłówko, Kleszewo, Niedanowo). Accepting the above attribution of the brooch from Tumiany to the Wielbark Culture the author gives an overview of the settlement and culture situation in the eastern reaches of the Olsztyn Lake District (Pojezierze Olsztyńskie) during the Younger and the Late Roman Period as well as during the Early Migration Period. At the same time, analysis is seriously constrained by the fact that most of the sites of the period were investigated before WW II and information on their subject is laconic and scattered in German regional literature and in archival sources. Despite these limitation of the database there is justification to place the eastern part of the Olsztyn Lake district within the range of Wielbark Culture settlement of the Younger Roman Period, with no conclusive evidence on its continuation in phase C3–D. At the beginning of the Late Roman Period we see the disintegration of Wielbark Culture settlement in a wider territory found in the drainage basin of the Łyna, Pasłęka and upper Drwęca Rivers caused presumably by the departure of the population on a great migration to the southeast (Fig. 3). Did everybody go away? The lingering of small groups is documented by isolated sites in a vast area of desolation eg, Woryty, grave 4. At the current stage of research it seems most likely that the caterpillar brooch from Tumiany is a relic associated with a small group of Wielbark Culture people who decided not to risk the long trek into the unknown or at least, to put it off for a time.