The Hymenoptera family Ichneumonidae is yet to be fully known and understood, we still expect that there are new species to be discovered in this family. Cylloceria, a genus within Ichneumonidae, is a genus with a lot of species names both synonymous and currently in use. How sure can we be that those species actually are different enough to be considered true species? In this study a part of the determined collection at the NHM in London was examined morphologically with focus on four known species (C. borealis (Roman, 1925), C.caligata (Gravenhorst, 1829), C. melancholica (Gravenhorst, 1820) and C.sylvestris (Gravenhorst 1829)) and one assumed to be a new species, to see if specimens of the five focus species are most similar within the species or if they are closer to specimens determined to other species. The other species present at the NHM of London (C. alvaradoi (Gauld 1991), C. arizonica (Dasch 1992), C. aquilonia (Dasch 1992), C. barbouraki (Gauld 1991), C. imperspicua (Rossem 1987), C. impolita (Dasch 1992), C. striatula (Dasch 1992), C. trishae (Gauld 1991) and C. ugaldevi (Gauld 1991)) were used as outgroups which made it possible to see if the five species keeps together in their species. In total 31 specimens of 15 species were examined using morphological characters. The data of collection sites and collection times of the specimens investigated morphologically enabled me to conclude approximately when and where both the five focus species and the genus Cylloceria are flying during the year. The five focus species flies from around May to September where only the species C. melancholica might have two generations. Cylloceria as a whole were found to have one generation from in April to July and one second flight period in November to January in South Mexico and Costa Rica, specimens collected north of there had only one generation in May to September. A cluster analysis was made based on eight of the morphological characters, the ones that were categorical excluding the ambiguous and constant characters. None of the five focus species formed species unique clusters but grouped with specimens from other speciesin the tree, although C. borealis was much more separated according to species than the rest. The result of the morphological analysis shows that there are much more to be done to get a clear definition of the five focus species including whether or not the possibly new species actually is a new species. I would believe that a future study with a genetic analysis in combination with morphological characters to know definitely which specimens that belongs to the same species, followed by a study of type specimens so that the found species gets the correct species name could make the uncertainties in the genera (Cylloceria) almost disappear. If the morphological characters analysed are later used to find out which characters that should be used in future morphological species determination then all current questions regarding the genus taxonomy will be solved.