Biosystematics of the grylloblattodea

Joseph William Kamp
The North American Grylloblattidae are either hygro-philic occupants of the alpine-subalpine or facultative cavernicoles of lava ice caves. The'research indicates that the habitats preferred by Grylloblatta must be cold and moist but not wet. The preferred alpine-subalpine hypolithion was found to be beneath stones 50 to 150 cm. buried 20 to 50 cm. deep in the substrate. Grylloblatta also temporarily occupied glaciers, snow fields, rotting logs and borders of glacial springs. The optimum
more » ... The optimum microclimate in the alpine-subalpine habitats was within - 3 to + 6° C. with a humidity above 70 per cent. Humidity evidently governs the occupancy of the hypolithion more than temperature. The insect will not inhabit hypolithion with relative humidities less than 70 per cent, regardless of temperature. The cavernicolous habitat for Grylloblatta is a micro-environment limited to a few ice caves in lava fields. Sufficient ice must be present to maintain a spring-to-fall temperature of - 3 to + 8° C. and over 80 per cent relative humidity. During the winter the Ice cave is recharged with cold air below the tolerance of Grylloblatta at which time the Insect inhabits the hypolithion. The temperature preference of Grylloblatta, established in the laboratory, was between - 3.5 and + 5° C. at 90 to 99 per cent relative humidity, - 2.2 to + 4.5° C. at relative humidities between 70 and 90 per cent, and - 1.1 to + 1.6° C. at 50 to 70 per cent relative humidities. Temperature tolerance at humidities above 95 per cent ranges between - 4 and + 11° C. Four-hour exposure to + 16° C. and one-hour exposure at - 5.5° C. produces 50 per cent mortality. Lethal extremes were - 8° C. and + 23° C. All stages of the insect were found to be active year around with no dormant period. The mean freezing point depression of the hemolymph was measured at - 0.98° C. therefore, the insect remains active in a supercooled state. Twenty-six new populations were found during this research, extending the distribution from the Yukon-British Columbia border [...]
doi:10.14288/1.0101053 fatcat:tu5yyjuckjc6rcfphtvk3oft5i