Due to the pet and goods trade, several animals are now present in regions outside of their traditional native ranges. A peculiar situation has arisen in mantises, insects that are becoming more popular as pets: two genera (Hierodula and Tenodera) have begun to spread around the world, with two Hierodula species overlapping in Europe and two Tenodera species doing the same in North America. Such an event can lead to possible competition with both local taxa and alien congeneric sister species; the latter may reduce the impact of one of the invaders. Additionally, the situation allows the comparisons of niche shifts in displaced mantises, allowing us to understand whether such animals respect general patterns shown in terrestrial ectothermic invasive species. To do this, I adapted scripts from previous publications for analyzing niche overlap (Schoener’s D), niche expansion (E), and unfilling (U) through the centroid shift, overlap, unfilling, and expansion (COUE) scheme using presence records from GBIF and iNaturalist Research-Grade observations and bioclimatic variables available in BIOCLIM, selected according to variance inflation factor (VIF) values. I also evaluated the overlap between the sister species in the non-native range with D. Overall, there was relatively high niche expansion and unfilling patterns shared among the taxa, although species tended to have low abiotic overlap between native and alien ranges, and a relatively high niche overlap was present among congeneric species in the shared non-native area. However, such analyses may be biased due to chosen variables, taxonomic uncertainty, and lack of information on mantises’ ecology; particularly, the situation regarding H. tenuidentata/transcaucasica should be monitored and clarified, given the higher potential invasion risk of these species compared to other mantises and the uncertainties regarding which populations have reached Europe. Additionally, the biology of alien mantises should be studied in more detail in both native and non-native environments given the current critical lack of information.