NO. 6 CHIGGER SUBGENUS GAHRLIEPIA — TRAUB AND MORROW 8l 



G. plurisetae, new species, and G. hirsuta (Radford, 1946), according 

 to our belief, the PLs have moved anteriorward until they are adja- 

 cent to ALs, and thus there appear to be two pairs of ALs. If such 

 were not the case, and the Jadin and Vercammen-Grandjean theory 

 were correct, in the case of G. dupliseta (fig. 70) one would have to 

 postulate the appearance of 2 sets of ALs, of which the second pair 

 is more than twice the length of the first, coupled with the disappear- 

 ance of PLs or the migration of the latter well toward the middle 

 of the scutum. 



HOST PREFERENCE AND HABITATS OF THE SUBGENUS GAHRLIEPIA 



Gahrliepiine chiggers have apparently attained their maximum de- 

 velopment in the oriental region (Audy, 1954) (in contrast to the 

 New World, for example, where only one species is known). Never- 

 theless, they are collected far less often than are Trombicula and 

 Euschongastia in southeast Asia. This is particularly true of the 

 subgenus Gahrliepia, especially insofar as concerns the species with 

 scrobiculate or honeycombed scutum. Despite intensive collecting in 

 Assam, Burma, Malaya, and Borneo by U. S. Army and Colonial 

 Office Medical Research Units, four scrobiculate species have been 

 described on the basis of only four or fewer specimens, as shown 

 in table 2. 



It is quite probable that this scarcity of Gahrliepia in collections is 

 apparent rather than real, and is due to our ignorance of the habits 

 of these chiggers rather than to low numbers in nature. For example, 

 until the 1953 Borneo expedition, G. ampullata, new species, was 

 represented by but one specimen, and G. laciniata, new species, was 

 known only from three specimens, collected from two different kinds 

 of rats. The latter species was collected readily only when it was 

 discovered that instead of clustering in the ears of the rats, as do 

 most Trombicula and many Euschongastia, G. laciniata invariably 

 was found singly and the specimens were strongly attached deep in 

 the skin at the base of the stout hairs or vibrissae on the bridge of the 

 nose or muzzle of the hosts. Inasmuch as the chiggers in situ were 

 head down, partially embedded in the hair follicle, and also appressed 

 to the stout hairs in areas where the fur was short and dense, it was 

 difficult to see these Gahrliepia without special search. Since they 

 usually stayed firmly attached even when the host had been dead two 

 days, they were not readily dislodged or activated by the usual collect- 

 ing techniques. Even the detergent washing method usually failed 

 to dislodge them. Once its particular attachment site was observed. 



