Fungi isolated from environmentally challenging habitats can have adaptations of potential value when developed as insect pest-controls. Fungal isolates collected from Antarctica, Geomyces sp. I, Geomyces sp. II, Mortierella signyensis and M. alpina, were investigated for (i) growth characteristics at 0-35[degree sign]C, (ii) spore production at 10 and 20[degree sign]C, (iii) viability following exposure to freezing temperatures, and (iv) insecticidal activity against waxmoths (Galleria mellonella L.), houseflies (Musca domestica L.), mealworms (Tenebrio molitor L.) and black vine weevils (Otiorhynchus sulcatus Fabricius). All isolates showed growth between 5-20[degree sign]C, with some showing growth outside this range. Geomyces isolates sporulated over a wider range of conditions than the Mortierella isolates. Spore germination at 10[degree sign]C was higher for Geomyces sp. II when this isolate was produced at 10 compared to 20[degree sign]C (greatest difference 74.6 vs 32.7%). All isolates grew, with the exception of M. alpina, following exposure to -20[degree sign]C for 4 weeks. Insecticidal investigations showed M. alpina and M. signyensis caused significant mortality of waxmoth and housefly larvae via injection and soil inoculation, and M. alpina caused significant mortality of housefly larvae via baiting; the Geomyces isolates had little lethal effect.