TRUE GUESTS, ECTO- AND ENTOPARASITES. 



4'S 



six are present, which rarely happens, four are arranged in pairs on 

 the sides of the head and gaster, while of the two remaining individuals, 

 one attaches itself to the gula, the other to the mid-dorsal surface of 

 the gaster. Janet believes that these symmetrical arrangements are for 

 the purpose of balancing the burden and thus making it easier for the 

 ants to carry. When attached to the head the mite obtains its food by 

 drinking from the regurgitated droplet as it is being passed to or from 



E 



.-O 



FIG. 251. Development of Orasema viridis. (Original.) A, First larval stage 

 of Orasema. B, pupal worker of Pheidole instabilis with Orasema larva (o) attached 

 to side of neck ; C ', female Pheidole pupa with somewhat older Orasema larva (o) at- 

 tached in sternal region ; D, female Pheidole pupa with Orasema larva (o) in same 

 stage as in preceding figure, attached behind head ; E, female Pheidole pupa (phthiso- 

 gyne) with older Orasema larva (o) in sternal region ; F, Orasema larva (o) begin- 

 ning to pupate, with vesiculate knobs on its surface ; G, Orasema pupa fallen from 

 its host and developing within the vesiculate skin ; H, fully formed pupa ; 7, pupa 

 pigmented and ready to hatch. 



the mouthparts of the host, or it titillates the ant with its antenniform 

 legs and induces her to regurgitate for its special benefit. The mites 

 attached to the gaster obtain their food by stroking other ants in the 

 vicinity or by reaching out and partaking of the droplets as they pass 



