10 INSECTS AFFECTING DOMESTIC ANIMALS. 
own substance. In the third group are placed those which simply ask 
protection or an opportunity to procure food in connection with, or to 
live upon cast-off portions or rejected matter from, the host. 
In later writings, many of which have appeared since the first writ- 
ing of this chapter, this grouping has been more or less modified, and 
a careful summary derived from the works of Leuckhart, Looss, Blanch- 
ard, Neumann, Railliet, and others is given by Dr. C. W. Stiles in the 
Proceedings of the Entomological Society of Washington. (Vol. III, 
p. 6.) This arrangement, in brief, is: 
A. Based on Symbiosis and food: (1) Mutualists; (2) Commensalists; (3) True 
parasites; (4) Pseudoparasites; (5) Spurious parasites. 
B, Based on position: (1) Ectoparasites; (2) Endoparasites. 
C. Based upon the animal or plant: (1) Phytoparasites: (a) in or upon animals; 
(b) in or upon plants; (2) Zoo-parasites: (c) in or upon animals; (d) in or upon 
plants. 
D, Based upon time: (1) Temporary parasites; (2) Stationary parasites: (a) Peri- 
odical parasites; (b) Permanent parasites. 
E. Based upon adaptation or necessity: (1) Facultative parasites; (2) Obligatory 
parasites. 
I’. Based upon the number of hosts: (1) Monoxenous parasites; (2) Heteroxenous 
parasites. 
A careful examination of the subject will show that none of these 
groupings furnish a satisfactory basis for a systematic plan of treat- 
ment, in a work of this character at least, since we may have a number 
of these roles assumed by the same insect at different periods of its 
existence or under different conditions. 
It has seemed, all things considered, the most feasible plan for this 
work to inciude all insects directly injurious to the animal economy, 
or directly associated with domestic animals, to take up the different 
species in their zoological order, so that similar forms may be treated 
together and repetition may be avoided, and to treat each species as 
fully as possible, giving its past history, extent of injury, habits, and 
life history, and finally methods of preventing or relieving its injuries. 
In order to furnish a convenient key to the different species and 
enable the different forms occurring upon one animal to be seen 
together, a table has been arré anged according to animals infested, 
constituting Chapter VIII. Then a chapter is devoted exclusively to a 
discussion of remedial measures, methods of prevention, and notice of 
animals which have parasites in common. 
The group of worms is excluded from this work, as it would too 
greatly extend it, and, moreover, the most important species have 
received quite thorough treatment in veterinary works and special 
treatises which are available to those desiring information regarding — 
them. Moreover, these parasites are less under the control of the 
breeder except in the way of prevention. 
In order to show more fully the relations of the parasitie species, a 
brief review of the classification of those included will be of assistance. 
