Interrelationships between Arixenia emu (Dermaptera) and molossid bats and their ectoparasites in Malaysia

. 1. Four species of Molossidae occur in Malaysia ( Cheiromeles torquatus and three Tadarida species) and from these, six species of potentially ectoparasitic insect have been recorded (two Etermaptera: Arixeniina; two Hemiptera: Cimicidae; two Siphonaptera: Ischnopsyllidae). 2. The two Arixeniina, Arixenia esau and Xeniaria jacobsoni are obligatorily associated with C. torquatus and only accidentally with Tadarida species with which C. torquatus often roosts. The nature of this association is presumed to be mutualistic and its origins are discussed. 3. A.esau can occur in great numbers in association with C.torquatus. It is primarily a roost dweller and is seldom found upon flying bats, although it is in this way that transference to new roosts must occur. It feeds mainly upon body exudates and skin debris from its hairless host. Aspects of its biology are discussed. 4. Arixenia species are usually found together with Xeniaria species but always greatly outnumber them. Differences between A.esau and X.jacobsoni are discussed. 5. The remaining four species of insect all feed upon blood and are truly parasitic, both species of bedbug and one flea being associated with C. torquatus and the other flea with Tadarida species. A.esau acts as a phoretic host for the flea host‐specific to C. torquatus. Lagaropsylla turba. Otherwise no interactions were noted amongst the six insects.