ANDROCHROMIC FEMALES IN SPECIES OF THE DR AGONFLY-GENUS AESHNA BY ADMINISTRATION OF HIGH-TEMPERATURES (ANISOPTERA, AESHNIDAE)

Fully developed female larvae and their freshly emerged imagines of 3 Aeshna-species [A cyanea (Muller 1764), A juncea (Linnaeus 1758) und A subarctica elisabethae Djakonov 1922] were kept at 16 degrees C and 3 0 degrees C in the laboratory for serveral weeks. FF of A caerulea wer e collected in the field shortly after emergence and were kept under n atural outdoor conditions with maximum day TT < 18 degrees C and 25-32 degrees C resp. All specimens originated from the Black Forest, SW-Ge rmany. All FF, except in A subarctica, kept at high TT gained the andr omophic blue colour of MM, while specimens kept at low TT developed to the normal heterochromic form. In A subarctica, TT had not any effect to body colour, and high TT did not 'produce' the interlineata-form a s suggested by JURZITZA [1964a] and PETERS [1987]. Also in the field, during the very hot summer period of 1994, more androchromic A cyanea- FF have been recorded than under normal conditions.