40 JOURNAL OP ECONOMIC ENTOMOLOGY [Vol. 1 



molting on the host, for example, by the various species of Margaropus 

 and by Dermacentor nitens. To this class belong several other species 

 which have partially overcome this disadvantage in their passing the 

 first molt upon the host. Two representatives of this class are the 

 South African species, Bhipicephalus bursa and evertsi. A species 

 of Haemaphysalis, which has recently been discovered by the writer 

 to occur frequently upon the heads of birds in the southern part of 

 the United States, also seems to have acquired this habit, at least 

 partially, for it has been determined by the molted larval skins that 

 the first molt is so passed. It has been overcome entirely by Orni- 

 thodoros megnini, the Spinose Ear Tick, in a somewhat different way, 

 that is, by passing the first molt upon the host, then feeding sufficiently 

 as a nymph, so that following the second molt, which takes place off 

 the host, engorgement as an adult is unnecessary for oviposition and 

 probably never occurs. 



Even in species most diverse in their tastes there are some hosts 

 especially favored; this in some cases may be accounted for by the 

 great numbers of that host. 



In the class which has adapted its habits to the habits of the host, 

 the ticks are confined largely to a host or group of hosts with similar 

 habits. In the studies of the ticks made by the writer, these adapted 

 habits have been found most interesting. The species Haemaphysalis 

 leporis palustris, commonly known as the Rabbit Tick, has adapted 

 itself to the habits of the Leporidae, the hares and rabbits, and only 

 accidentally attaches to other hosts. It is the habit of the hares and 

 rabbits to remain more or less inactive during the day in their 

 "forms" or resting places, protected by a clump of grass or bushes 

 from enemies such as birds of prey, their activity being largely at 

 night. The writer has found that this tick following engorgement 

 drops largely during the day, in other words when the hares and rab- 

 bits are in their forms or resting places, to which places they or others 

 return to pass the day. Thus, when the ticks have hatched or molted 

 and are ready to attach, they have little trouble in finding the host. 

 This same habit has been acquired by the Fowl Tick, Argas miniatus, 

 which in the engorged larval stage, the writer finds drops only at night 

 (except accidentally) when its host, the fowl, is upon the roost. Thus 

 when ready to re-attach it is near and readily finds the host, whereas 

 had it dropped during the day when the fowl was on the "run" the 

 chances of its finding a host would be greatly lessened. A habit ap- 

 parently acquired by Ornithodoros megnini is that of crawling to a 

 height of several feet from the ground as a nymph before molting and 

 depositing its eggs; thus when the seed-ticks appear ready to attach 

 they will be rubbed off by the horse, cow or other host and readily find 



