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Journal of Agricultural Research 
Vol. XXVI, No. 9 
it becomes apparent that there is agreement in all the essential characters; 
thus the writer feels confident in pronouncing our common species 
tlalzahuatl. 
As to the common name of tlalzahuatl: In view of the fact that the 
name Mexican chigger has not been very generally used and is now, 
according to our most recent knowledge of the distribution of this species, 
inappropriate, the writer is taking the liberty of suggesting here a new 
common name for this species. That of the common North American 
chigger would be distinctive, or the species could be called just the 
North American chigger, as it far exceeds all others in numbers and 
importance and is the only one attacking man and domestic animals 
that is distributed over a large portion of the continent. 
: Recently Hirst 3 has figured under the name of Leptus (Trombicula ?) 
similis a chigger taken from chickens in the United States which is identi¬ 
cal with the common one infesting chickens and attacking man and 
apparently all of our domestic animals—i. e., Trombicula tlalzahuatl 
(Murray). 
It is probable that the chigger described by C. V. Riley 4 as Leptus 
irritans is no other than our common species. Until a further study is 
made of the exceedingly poor specimen of irritans left in the old Riley 
collection, this point can not be settled definitely. About all that 
remains of this injured Riley specimen is a jaw. Knowledge of the 
structure of the chelicerae alone has been insufficient in the past for 
specific determination but may soon prove sufficient as our knowledge 
increases. 
The adult form of our common chigger is very probably Trombicula 
cinnabaris Ewing, 5 the only Trombicula adult known to be widely 
distributed in the region infested by Trombicula tlalzahuatl (Murray). 
Specimens of Trombicula tlalzahuatl (Murray) 6 have been determined 
by the writer from the following localities and hosts: 
New Jersey: 
Pemberton, one specimen from man, July 19, 1915 (H. K. P.). 
Pennsylvania: 
Stone Valley, Huntingdon County, many specimens, August 3.. 1922 (D. L. Van 
Dine). 
Maryland: 
Berwyn, four specimens from man, July, 1919 (A. B. Gahan). 
Bannockburn golf grounds, near Glen Echo, one specimen attached to man, 
summer of 1919 (H. E. Ewing). 
Chesapeake Bay, hundreds of specimens attached to king snake, summer of 1920 
(W. Palmer). 
Somerset, several specimens attached to man, August 16, 1919 (H. E- Ewing). 
North Beach, one specimen attached to man, September 21, 1919 (H. E. Ewing); 
many specimens in leaves and trash, also on man, summer of 1921 (H. E. Ewing); 
many specimens on and attached to man, summer of 1922 (H. E. Ewing). 
Takoma Park, several specimens attached to man, summers of 1921 and 1922 
(H. E- Ewing). 
Virginia: 
East Falls Church, a few engorged specimens in scrapings from concealment 
nest of rabbit, August 2t, 1919 (H. E. Ewing); many specimens in trash on 
surface of ground and attached to man, summer of 1919. 
Great Falls, two specimens attached to man, August 18, 1919, and one specimen 
attached to man, August 24, 1919 (H. E. Ewing). 
3 Hirst, Stanley. 192a. mites injurious to domestic animals. Brit. Mus. Nat. Hist. Econ. Ser. 
No. 13, P- 78. 
4 Riley, C. V. 1873. harvest mites. In Amer. Nat., v. 7. P. 17-18, fig. 5b. 
6 Ewing, H. E. 1920. the genus trombicula berlese in America and the orient. In Ann. Ent. 
Soc. Amer., v. 13. P- 387-389. fig- 3 - 
3 Murray, Andrew. 1877. economic entomology, aptera. p. 113. London. 
