The mode of attachment of mite larvae (Leptus spp.) to harvestmen (Opiliones)
Larval mites of the Leptus group (Family Erythraeidae), ectoparasitic on adult harvestmen, deposit at the attachment site a cementing substance forming a superficial cone that concurrently with the distension of the distal portions of the inserted chelicerae promotes firm anchorage in order to ensure the long attachment of the larvae to the host. The larvae, which suck up haemolymph plasma and tissue fluids, were not found to develop a stylostome. Violent defence reactions by the host have not been demonstrated. While granular haemocytes migrate to the bite site they do not establish cell aggregations or capsular formations. A coat of coagulated haemolymph plasma, presumably not mediated by the granular haemocytes, is deposited on organic structures at the bite site. A melanization of the coagulum has not been recognized. The non-appearance of a stylostome is thought to be connected with the mild defence reactions on the part of the host.