[Cold tolerance of the Pharaoh's ants (Monomorium pharaonis)]

The reaction of Pharaoh's ants to low temperatures was analyzed under laboratory conditions. It was to be clarified in which way low temperature could be used in control measures. In all of the examined ranges of temperature from + 8 degrees C up to --26 degrees C colonies of the Pharaoh's ants were eradicated. The necessary exposition times reached from 30 minutes at --26 degrees C up to nearly 3 weeks at + 8 degrees C. Most favourable for control measures are temperatures near 0 degrees C which lead to the eradication of large colonies within 6 days. The queens were especially susceptable to temperatures below 0 degrees C, whereas temperatures at 10 degrees C are tolerated much better by queens than by workers. In the developmental stages the eggs and the youngest larvae are most resistant, whereas the full grown larvae including sexual larvae die fast. The results demonstrate that using the winterly temperatures in Middle Europe as an integratory method in the control of the Pharaoh's antis of considerable value.