2 BULLETIN 986, U. S. DEPARTMENT OF AGRICULTURE. 
Leptus americanus and Leptus irritans. Although these names have 
been used frequently in American literature dealing with economic 
entomology, and the figures of Riley’s two species often copied, the 
present writer is bound to confess that after studying carefully 
Riley’s descriptions and figures and some of his microscope slides 
(types?) he has been unable to correlate either americanus or irritans 
with the two species with which he is familiar. Further than this, it 
can now be fairly definitely stated that americanus is not a species of 
Trombidiidae at all, but is rather a species of the family Eryth- 
raeidae, a group to which the genus Leptus really belongs, as Riley’s 
figure clearly shows. Leptus irritans is 
the larva of a species of Trombidiidae, 
but the characters given by Riley are not 
even of generic value; hence it appears 
that it will never be known certainly what 
species his irritans is. 
In New Jersey, Maryland, the District 
of Columbia, Virginia, and southeastern 
Towa there is apparently a single chigger 
species. The writer has examined many 
specimens from these sections and finds 
that they are all the same. 
In the northern and western part of 
the United States there is another very 
Fig. 1.—Dorsal view of an : apace 
American chigger (legs omit- Closely related species which has the 
ted), % et This drawing body shaped exactly like the first men- 
was made irom specimens in . - 
the University of Minnesota tioned but has more dorsal spines on the 
collection, which were taken gbdomen, and fewer branches or barbs 
at Lake Minnetonka, Minn, AA : 
on the palpal sete. This is the species 
studied by C. W. Howard (6). Specimens have been examined from 
Minnesota and Kansas. 
NOTES ON SEASONAL HISTORY. 
Chiggers are especially pests of the summer months, as has long 
been known, but the period of their activity has not been known, 
even relatively. During the year 1919, at Washington, D. C., the date 
of the first record of larve attaching themselves to man was July 2, 
and by July 17 larve were present in great abundance. On the 
latter date the writer was severely attacked. During the remainder 
of July and the whole of August the chigger larve continued in 
great abundance, and almost daily records of their attacks were 
obtained. In September the attacks were much less severe, yet con- 
tinued. On September 22 several larve attached themselves to man 
at Chesapeake Beach, Md. No records for the northern part of the 
United States of chigger attacks in October have been brought to 
