8 BULLETIN 986, U. S. DEPARTMENT OF AGRICULTURE. 
due to chiggers, were found to be due to Hyletastes missouriensis 
Ewing, a gamasid mite, the habits of which are not well known. 
Injury from fieas is very similar to the first-stage injury of chig- 
gers, and since fleas soon leave their hosts and chiggers are so small 
that they frequently are overlooked, flea injury is mistaken for 
chigger injury. A careful examination with a hand lens will enable 
one to see the attached chiggers and prevent confusion of flea injury 
with an attack by chiggers. 
DO CHIGGERS PENETRATE THE SKIN? 
Both among entomologists and the public generally there is a 
belief that chiggers burrow into the skin. C. V. Riley (0) states 
in regard to his zrritans that “This mite 
is able to bury itself completely in the 
flesh.” In speaking of the same chigger, 
Osborn (8, p. 252) sys: “It is brushed 
from the leaves of various plants onto the 
hands or clothing of people and to the 
bodies of other animals, and the mite then 
proceeds to burrow into the skin.” 
To find out whether chiggers penetrate 
the skin or not, and also to observe their 
==} injury, resort was made to experimenta- 
tion. On July 15, 1919, the writer exposed © 
Fig. 3.—View shewing the ° 
method of attachment of a the left calf and ankle to chigger attack, 
chigger (northeastern spe- : 
Be ce ete pan ry and after the mites had settled numbered 
of a “slice” of skin, made 10 individuals by writing on the flesh near 
Fn ee tae ar a aed the mite with ink. Daily observations were 
made on these chiggers, using low and high 
power lenses, for the next eight days. It was observed on the first 
day that the mites attached only by their mouthparts and in no way 
burrowed into the skin. Observations on the second day showed no 
change; in fact, after once attaching to the skin by their mouthparts 
the larve became quiescent and did not change their position until 
they dropped off. ? 
By means of a razor blade several individuals were removed by 
slicing off a small area of the epidermis around them. When this 
“slice” of epidermis was examined under a high-power micro- 
scope objective it showed the attachment as represented in figure 3. 
The hooked and ventrally barbed chelicere were thrust into the 
epidermis only, and the palpal claws were found forced downward 
and backward into the epidermis. After both the chelicere and 
the palpi have been inserted in this fashion they hold the larva 
locked, as it were, to the skin. This was made evident by watch- 
