INTRODUCTION. 13 
which prey upon young fish. The common Belostoma americanum and 
the Benacus griseus may prove at times quite destructive in this man- 
ner, and if fish culture should become an important industry for the 
utilization of ponds and streams, and such species as the carp be kept 
in a state of practical domestication, such insects might be thought 
to come within the scope of our work. The adult insect is strongly 
attracted by electric lights, and in many localities has received the 
name of ‘“ electric-light bug.” Not infrequently curious observers are 
made to suffer from the punctures of its powerful beak. Should the 
species require practical attention its gathering at lights could be made 
the basis of effective measures for its reduction. At present it need 
not be considered as requiring notice in a work of the scope assigned 
to this paper. 
In the homopterous division of the Hemiptera no species are known 
to be of importance in this connection. 
The suborder Parasita includes the families Polyctenide and Pedi- 
culidz, the latter of which only is of consequence as affecting domestic 
animals. These are degraded, wingless forms occurring on nearly all 
species of mammals, and may be considered as the most truly parasitic 
of any of the forms we shall consider, their whole existence being con- 
fined to and dependent upon a certain host, 
The group of Mallophaga, including the bird lice, has been of some- 
what doubtful position, but at present authors are generally agreed that 
they have their affinities with the Pseudoneuroptera, in which group 
they naturally fall near the family Psocidz, which includes the minute 
book lice so common in books, herbariums, insect collections, etc. The 
group is well marked, though somewhat aberrant, doubtless a result of 
the very distinct parasitic habit of all the species. It is unnecessary 
to go into a discussion of its zoological position here. The species are 
all entirely wingless and may be easily distinguished from the Pedi- 
culide by their biting mouth-parts, the jaws being well developed. 
They are all confined to warm-blooded animals, birds and mammals, 
by far the greater number being parasitic on birds. 
The group contains two well-marked families,! quite easily separated 
by the structure of the feet. The Philopteridze having but very short 
tarsi and being unable to travel rapidly, while the Liotheidz have well- 
developed tarsi and run with great rapidity and ease. 
The Neuroptera proper, which is divisible into several orders, does 
not contain any species that are to be counted among the insects 
affecting domestic animals directly. 
The Thysanura, including the little spring tails, would scarcely seem 
likely to present any parasitic forms; but Mégnin? has described a 
species, Podurhippus pityriasicus, as affecting horses parasitically. 
The Arachnida are for the most part readily separated from the 
1 Kellogg, in his “‘ New Mallophaga,” proposes a new family arrangement, making a 
family Trichodectidw for mammalian philopterids. 
? Les Parasites and les Maladies Parasitaires, p. 104. 
