The Chigger-Mites Affecting Man and Domestic Animals

H. E. Ewing, Albert Hartzell
1918 Journal of Economic Entomology  
Although the chigger-mites are widely known over the world on account of their attacks on man and domestic animals, yet, because of their minute size, they have been remarkably exempt from thorough investigations which usually have been applied to pests of so much economic importance. In Europe, due chiefly to the work of Dr. Oudemans and to Berlese, we have recently learned much of the taxonomy, biology, habits, and distribution of the foreign chiggermites. As is well known among
more » ... among entomologists, chigger-mites are the larvre of the brilliantly colored harvest mites, which,\ according to acarologists, are placed in the family TROMBIDlIDlE. This fact, however, was not known when many of our common chiggers were first described, or if known was not heeded. When these early descriptions were made, the larval characters of real taxonomic importance had not been worked out, so that these descriptions have proved to be all but valueless to us today, notwithstanding we now have an excellent key to the chiggers based on larval characters. In this paper it has been the object of the writers to give a summary of the important biological and other facts concerning the chiggermites known to affect man and domestic animals, together with references to a few important species found in this country which so far have not been recorded from these hosts. To the recorded observations of others we will add what we have learned of our American chiggers. Some of the species here mentioned have not been sufficiently known in the past to have acquired' common or popular names, hence one of our chief tasks has been to get appropriate common names for these less known chigger-mites. THE SUMMER CHIGGER OF EUROPE [Metathrombium poriceps (Oudemans)] (Fig. lOa) Chigger-mites have been studied more in Europe than in America, and it is now known that at least three different species are concerned in the attacks upon man and domestic animals. Of these three species, two are quite common, one attacking in the summer time, the other in' the fall. The summer chigger-mite of Europe is a very small creature not more than 0.4 mm. in length when unengorged. It is egg-shaped, and has above on the thorax two porous chitinous plates or shields. by guest on June 5, 2016 Downloaded from
doi:10.1093/jee/11.2.256 fatcat:s4nx32qbrbgtph37wypq7dtlaa