16 BULLETIN 986, U. S. DEPARTMENT OF AGRICULTURE. 
A well-known golf course was laid out west of the District of 
Columbia in a region heavily infested with chiggers. Later an 
investigation showed that the sodded areas where the balls were 
played were quite free from chiggers. When persons went into the 
patches of rough growth between or around these areas they were 
attacked by SSeree 
A chigger- infested lot in East Falls Church, Va., was cleared of 
rough growth and a house put on it during the summer of 1919. 
These operations destroyed the breeding places of the chiggers. 
Of all the growths that favor the harboring of chiggers none is 
more favorable than wild blackberries cr wild dewberries. Wild 
blackberry patches in Virginia and Maryland invariably were found 
to harbor immense numbers of chiggers. Where such patches are 
located at very objectionable places their obliteration would seem 
justified. The fruit produced by these wild canes is of a good quality, 
however, and constitutes not a small item in the summer food supply 
of the country: hence a wholesale destruction of wild blackberries 
would be both rash and foolish. 
Dr. Chittenden has mentioned (2) the value of cattle and even 
of the passing of many persons in destroying chiggers. In 1914 (3) 
he published the results of a conversation which he had with Mr. 
William N. Irwin (through an error given as E. F. Erwin). 
who before his death was connected with the Department of 
Agriculture; in this conversation Mr. Irwin stated that he con- 
‘sidered cattle inadequate where a large area was to be dealt with. 
He claimed, however, that he had experienced good results where 
sheep were used instead of cattle. The efficacy of sheep in chigger 
eradication thus being shown, an explanation of their agency and its 
effect on the chiggers is due. Dr. Chittenden claimed that the vaiue 
of cattle in chigger control came from the trampling of the pests, 
and he would explain in the same way the benefits from the utiliza- 
tion of sheep, adding, however, that the sheep are prebably more 
effective, by “ keeping the grass more tightly cut than would cattle.” 
Mr. Irwin explained the agency of the sheep as being due in part 
to the ascent of their legs by the chiggers and their destruction 
through contact with the oil in their wool. The present writer would 
explain this observed difference between the efficacy of cattle and 
sheep as being due chiefly to the food habits of the latter, the sheep 
not only keeping the grass more closely cropped, but also feeding 
to a considerable extent on the leaves of shr ubbery. 
Just what the value of a certain amount of shrubbery is to chig- 
gers is not known in the case of our species. It may furnish a favor- 
able environment for the natural hosts of the parasites. or furnish 
the necessary environment for either the nymphs or adults of the 
chiggers, or both these instars, or furnish a proper environment for 
the larve. 
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