258 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 11 
This chigger has been frequently reported from man. It also has 
been taken from the dog, and from chickens. Among the invertebrate 
hosts we find the house-fly ( Musca domtstica) , many small dipterous 
insects as well as insects belonging to the following orders: Orthoptera, 
Ryhnchota, Diptera, Coleoptera, Lepidoptera and Hymenoptera. It 
has been recorded from spiders, from rodents, and from various mam¬ 
mals. This mite has been collected during the months of June, July, 
August and September. It is found in the Netherlands, France and 
Germany; and doubtless occurs in other parts of Europe. 
The European Autumnal Chigger 
[Microthrombidium pusillum Hermann] 
It is the autumnal chigger-mite that has become noted because of 
its attacks on man and beast in Europe. This chigger-mite was long 
known under the name of Leptus autumnalis, and gave rise to a severe 
i 
rash or itch which was called “ erythema autumnale.” 
When unengorged these chiggers are very minute, being scarcely 
visible to the naked eye. They are brick red in color, and ha ye above 
one dorsal median shield, which is trapezoidal in shape. 
It was for a long while believed that this mite, as well as chiggers 
generally, lived on the juices of plants and that only under certain 
conditions did it become blood thirsty. C. V. Riley shared this belief 
with others, and stated as follows in regard to one of our American 
chiggers: “I have stated my belief that its normal food must, appar¬ 
ently, consist of the j uices of plants and that 1 the love of blood proves 
ruinous to those individuals who get a chance to indulge it.’ ” 
The belief that chigger-mites lived normally on the juices of plants 
gained credence no doubt largely on account of Claparede’s conten¬ 
tion that they belonged to Tetranychus, a genus composed of plant¬ 
feeding acarids. 
This chigger, like all other species of its genus, lives normally upon 
invertebrate hosts, especially insects, and is an accidental parasite 
only on higher animals. Besides being especially severe when on man, 
it is troublesome to horses, cattle, sheep, rabbits, dogs, and cats. 
When first attacking they attach themselves by means of their claws 
and palpi. Around the attached chigger, swellings are said to develop 
which may be as large as a pea or larger, and there is severe itching. 
It has been stated that fevers result at times after mite attacks, hence 
it is believed by some that this species, as well as others, gives off a 
toxin. This chigger has been reported for the months of September, 
October, and November. 
Various insects are reported as being hosts for this mite, and are 
probably the normal ones. Among the other hosts reported are dif- 
