242 Transactions of the Academy of Science of St. Louis 
point was exposed dorsally the staphylinid turned over on its 
back and grasped the June bug ventrally between the head and 
thorax. As soon as the June bug was killed the thorax was 
torn from the abdomen and a large amount of the viscera eaten. 
If a part of the June bug was moved with a probe the staphy- 
linid would attack again and retain its hold until all movement 
ceased. One could easily hear the crunch of the mandibles 
as each onslaught was made on the chitinous shell. 
It is not probable that the staphylinids swallow much of the 
solid portion of their food. In all cases under observation I 
found no instance in which it appeared that they were actually 
ingesting the solid substances, but rather they appeared to be 
extracting the juices and then discarding the more solid parts. 
I am very certain that the larvae do not ingest the solid food 
particles. The larva of Staphylinus maculosus would take the 
ant larva, ant pupa or termite and crush it between the mandi- 
bles and the clypeo-labral margin while the labium lapped the 
morsel. When the food began to work out from the mouth 
parts the larva would push it back with the anterior tarsi. Chew- 
ing would continue until the food material had been reduced 
to a dry pellet. If several termites were placed in the culture 
at one time the larva would paralyze, by crushing, all near it 
before beginning to feed. There is very little difference between 
the methods of feeding of the larvae and adults. 
As Parasitoms. There can be no definite line drawn be- 
tween the behavior of the parasite and the predator. Our only 
method of measurement is the effect upon the attacked organ- 
ism, as both parasites and predators live at the expense of 
others. Organisms which are unmistakably predacious attack 
and devour their victims. The parasite on the other hand, al- 
though it draws its food from another organism, is not immedi- 
ately fatal to the host. Fatality to the host in a truly parasitic 
relationship is not caused by the feeding of the parasite but is 
caused either by general exhaustion, produced by the withdrawal 
of the food containing materials or by the actual increase in the 
number of parasites. 
A perfect parasitic relationship is one in which the host 
organism is not seriously harme the presence of the para- 
site for when the host is killed the parasite must find another 
host or die. This ideal parasitic adjustment can be effected 
only in relationships of long standing and those organisms which 
seem to be parasitic but which quickly kill their hosts, may be 
considered to have only recently acquired this behavior. 
Beginning in 1870 when Sprague published his account of 
breeding Baryodma anthomyiae (Sprague) from the puparia of 
