Sil 
wards of a hundred spiders. And yet the latter are usually abun- 
dant enough. Their beneficial nature may sometimes be ques- 
tioned, inasmuch as they are often cannibals, and do not discrimi- 
nate between beneficial and injurious insects as food. 
A very large number of wasps prey upon caterpillars, locusts, 
flies and beetles ; others attack bugs. One genus of wasp ( Larra) 
makes the mole-cricket, Gryllotalpa, its common prey; and the 
observing person living in districts where grasshoppers abound 
cannot fail to note that these are preyed upon by certain wasps. 
Hacker (1918) records the big Australian eumenid Monerebia 
(Abispa) ephippium Fabr. ee on the larva of Clania igno- 
bilis Wlk., one of the bagworms (Psychidae), a family of moths 
containing some noxious species. 
The big wasps of the genus Monedula prey largely upon Taba- 
nidae @Elonce. flies ). Of M. surinamensis Bape. Belt (1874), p. 
239, says: “Horse-flies (Tabanus) were too numerous, an drops 
of blood trickled down our mules’ faces where they had feasted. 
In some parts large, banded black and yellow wasps (Monedula 
SUYINAMENSIS asia ) came flying round us and had a threatening 
look as they hovered before our faces, but they were old acquaint- 
ances of mine in Brazil, and I knew that they were only searching 
about for the horse-flies with which they store their nests. * * *” 
The Scoliidae are eminently beneficial—as is known to econo- 
mic entomologists. They destroy the larvae of the cocoanut 
beetles (X ylotr upes and Oryctes), and smaller species are known 
to prey upon the larvae of the so-called May or June beetles. 
The marked success of Scolia manilae Ashm., a rather small 
Philippine wasp introduced by this Experiment Station, into the 
cane fields of Hawaii, in checking the grub of the Anomala beetle, 
indicates that the Aculeate wasps have a place in the list of bene- 
ficial insect importations. 
In concluding, I may say that the nests and the burrows of 
solitary wasps and of some social kinds as well may be robbed 
with almost invariable impunity. Solitary wasps are never ag- 
gressive to the degree exhibited by their social brethren, and 
while they would sting or endeavor to do so were they incau- 
tiously held between the fingers, their weapon is directed mainly 
aoaimsptieir prey... hey do not appear to sting in the quarrels 
among themselves. But we know from reliable sources—such as 
experience—that hornets and many other social wasps behave 
otherwise ; they are bold in their strong communities and protect 

* According to Froggatt (1907), the large, metallic-blue thynnid (Diamma bicolor) 
of SE. Australia will, in the female sex, which is equipped with a powerful sting, 
turn on her back and fight furiously when molested. 
Gs 
