78 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



the parasites was so great that a pronounced dermatitis had 

 been set up. This occurred oftenest in fully adult and old 

 individuals in which the coat was coarse and scanty. 



With the exception of two nymphs taken from one Mns 

 norvegicus, all of about 3000 of the ticks examined were larvae, 

 it being evidently the habit of the species to drop from the 

 rodent host before molting into the nymphal stage. 



A number of full-grown larvae which survived anaesthesia 

 were preserved alive, and though attempts to induce them 

 to reattach to white rats failed, they molted, and as nymphs 

 survived without food for about five months, during which 

 period at least one molt occurred. 



The feeding habits of the nymph are not known to me, 

 but in Panama, as is known to be the case elsewhere, the adult 

 attacks man, adopting the habits of the bedbug. Whether 

 the rat shares with man the attentions of the adult tick I 

 do not know, though this is indicated. 



From the abundance of the larvae upon Panama rats, the 

 adults should be numerous in the houses of the poorer classes 

 in that city, but efforts to secure specimens were unavailing. 

 It is probable that the inhabitants do not distinguish accurately 

 between the species and Cimex lectnlarius, specimens of which 

 latter were invariably brought when "mamones," the native 

 name for this tick, were asked for and promised by the col- 

 lectors. 



They occur in villages of the interior, Dr. Darling having 

 collected them at Chorera, where the people showed evidences 

 of their attacks. Their abundance there is probably less than 

 in Panama if the numbers of the larvae observed in the latter 

 place is a sufficient indication. This may be due to the fact 

 that Mns nittus is the common house rat of the country 

 districts, while the brown rat prevails in the urban portions 

 of the city of Panama. This hypothesis implies that the 

 preference manifested by the tick for the brown rat is constant 

 and not due to local conditions, further observations being 

 necessary to establish the fact. 



I believe this to be the first record of the domestic rat 

 serving as host for the larvae of Ornithodoros talaje. The 

 double role as parasite of rodent and man played by this 

 species, suggests the .possibility of disease transmission from 

 one to the other of these hosts. 



