34 LEAFHOPPERS AFFECTING CEREALS, ETC. 
. 
SPIDERS. . 
The great abundance of spiders in pastures, meadows, and grain- 
fields is often most manifest by the immense number of webs that 
may be seen, especially on dewy mornings. These webs, however, 
tell only part of the story as there are a great many species of jump- 
ing and running spiders which construct no web to capture their prey 
and among these there are to be counted some of the most numer- 
ous and active insect feeders of the fields. These spiders are often 
taken in large numbers when sweeping for leafhoppers and that they 
feed readily upon the hoppers is proven by finding them with hoppers 
in their grasp within a few seconds after their capture in the net. 
Direct observation on unconfined individuals is difficult, since both 
spiders and leafhoppers are so hard to watch, but enough has been 
seen to justify the opinion that spiders are among the most widely 
distributed constant and effective agents in keeping leafhoppers in 
check. Exact observations on particular species to determine their 
relative value as leafhopper feeders, and to learn as to the relative 
value of adults or young spiders in such captures and their relative 
attacks on young and adult hoppers would be of great interest. 
Very likely the younger or weaker hoppers are preyed upon, especially 
by the smaller species or the young spiders. Mr. J. H. Emerton, 
the well-known authority on spiders, informs me that many different 
species are useful in this manner and he has kindly indicated a 
number of the species that he believes to be most efficient in this 
manner. Among these are the Xysticus triguttatus Keys., a species 
especially abundant in grasses and well adapted for leafhopper capture, 
and the different species of the genus Misumena, which are abundant 
in grasslands and low vegetation even up to high altitudes. 
The species of Philodromus are among the forms that construct no 
web, but capture their prey at large and are active feeders on leaf- 
hoppers. The genus Phidippus, including a number of species of the 
jumping spiders, are also very active in this work. 
The species of Dendryphantes, especially militaris Hentz and 
suturalis are considered by Mr. Emerton as among the most active 
leafhopper feeders. 
Mr. Nathan Banks, another well-known authority on spiders, has 
given me the following list of species which probably feed on leaf- 
hoppers: 
Epeira trivittata Keys., one of the most common web-making 
species; Oxyopes salticus Hentz, which is very common in the South; 
Thanatus rubicundus Thor.; Phidippus, especially the young, and 
mostly P. rufus Hentz and P. audax Hentz; Thiodina retarva Hentz; 
Tutelina elegans Hentz; Agelena nevia Walck.; Mangora gibberosa 
Hentz or M. maculata Keys.; Plectana stellata Hentz; Epewra pra- 
tensis Hentz; Tetragnatha laboriosa Hentz. 
