66 



REPORT 108, U. S. DEPARTMENT OF AGRICULTURE. 



Fig. 124.— Shield of nymph oi Ambly- 

 omma. (Original.) 



ings for several feet, molts, mates, and then begins to oviposit, placing her eggs in a 

 crevice. The mother then dies. The lan-se, upon hatching, remain in a bunch until 

 an opportunity for attachment occurs, when they seek the ear of their host. The first 



molt is passed on the host, and the nymph often 

 remains attached for a longtime. The female, if 

 she does not find a mate, may live for at least 18 

 months. Specimens kept in pill-boxes have pro- 

 duced slight tapping sounds. 



The Ixodidae, or true ticks, are represented by 

 a large number of species in tropical countries, 

 but in the temperate regions they are much less 

 common. However, there are about 40 species 

 in the United States, and one of these, the Texas 

 cattle tick, is a pest of prime importance. Various 

 classifications of the Ixodidae have been presented 

 by a variety of authors, most of whom relied on 

 the comparative length of the palpi as a primary 

 character. This, however, is not sufficiently different to be easily recognized; Lahille 

 based a classification mostly on sexual characters, as the presence and number of 

 ventral plates in the male. 



The following arrangement is more satisfactory, and applies also to the nymphs: 



1. Venter showing a curved groove (fig. 106) a short distance in front of the 



anus, and extending back each side to the hind margin; no posterior mar- 

 ginal festoons; stigmal plate nearly circular; no ocelli; hind coxae of male 



not enlarged 2 



Venter sho^ving more or less distinctly a curved groove behind the anus, 

 but none in front of it; the male with distinct marginal festoons, more or 

 less distinct in the female 4 



2. Legs longer than body; tarsi six to ten times as long as broad; coxae I hardly 



spinose;onbats Haemalastor. 



Legs shorter; tarsi much shorter; coxae I usually with spine or process 

 behind ". 3 



3. Capitulum slightly angulate on the sides; palpi with the third joint shorter 



than broad, and broadly rounded Ceratixodcs. 



Capitulum not angulate on the sides; palpi with the third joint longer than 

 broad and slightly tapering to tip Ixodes. 



4. Sides of capitulum angulate; ocelli usually present; male usually with anal 



plates; palpi very short 5 



Sides of capitulum not angulate 7 



5. Ocelli present; male with anal plates 6 



Ocelli indistinct, only a faint spot; male without anal plates; palpi without 



transverse ridges Rhipicentor. 



6. Palpi with acute transverse ridges Margaropus. 



Palpi without transverse ridges Bhipicepholus. 



Outer angle of the second joint of the short palpi acutely produced ; no ocelli; 



male without anal plates HaemaphysaUs. 



Outer angle of the second joint of the palpi not produced 8 



8. Palpi longer, second joint about twice as long as broad ; coxte IV of male not 



enlarged; basal part of tarsi I, II, and 111 shorter than apical part 9 



Palpi shorter, second joint barely longer than broad; coxae IV of male 

 enlarged; basal part of tarsi I, 11, and III subequal to apical part; ocelli 

 distinct Dcrmacentor. 



9. No ocelli ; male with anal plates Aponomma. 



With ocelli 10 



10. Orelli marginal; male without anal plates Ambhjo77imn. 



Ocelli a little above the margin; male with anal plates Ilyalomma. 



Our own species of Margaropus (M. ammlalus Say) (boiis Riley) (figs. 109, 110), is 

 the vector of Texas fever, a disease of cattle that causes enormous losses in the South, par- 

 ticularly in cattle imported there from the north. The southern cattle tick is found 

 only in the Southern States and the Government maintains a quarantine line where 

 cattle brought north may be cleansed of their ticks. The female tick is of a dark, dull- 

 brown color, with a reddish scutum and legs; the male is reddish brown, the legs paler 



7. 



