50 
These Dipterous parasites appear to be extremely rare, In every 
locality visited I dissected large numbers of locusts belonging to various 
species, but did not find any of them to contain a trace of these para- 
sites. I also brought a large number of the locusts home with me, but 
up to the present date no parasites have issued from them. 
Quite a large number of locusts were infested with small red mites, 
presumably Trombidium locustarum Riley, but these did not occur in 
numbers sufficient to prove fatal to the locusts they infested. 
On page 263 of the Second Eeport of the United States Entomological 
Commission, Professor Riley records having bred two different kinds of 
Bee-flies from larvae found feeding upon the eggs of locusts in Sierra 
Valley, California, the two species being Aphoebantus mus O. S. (of 
which Triodites mus is a synonym) and Systcechus oreus O. S. ; but, 
although I was especially on the lookout for specimens of these two 
species, I saw only a single specimen of the Aphoebantus. This was 
in Tehama County, and the specimen was resting upon the doorstep 
of a dwelling house. During the entire three weeks that I spent 
in investigating the locusts, the greater part of this time having 
been spent in the fields, I did not see another specimen of this species, 
nor of any other species belonging to this or to closely related genera. 
The Bee-flies that I saw belong to the genera Toxophora, Geron, An- 
thrax, Argyramceba, and Exoprosopa, none of which in the larva state 
are known to feed upon the eggs of locusts nor to attack the locusts 
themselves. Here in southern California I have collected specimens 
belonging to twenty-two different species of Aphoebantus, several of 
which occur in quite large numbers j and it is evidently largely due to 
the presence of these insects that the locusts so seldom occur in 
destructive numbers in this part of the State. 
In the first report of the United States Entomological Commission, 
pages 297 to 301, Professor Riley gives an extended account of the 
early stages of three different species of Blister-beetles, the larvae of 
which he found feeding upon the eggs of various kinds of locusts in the 
region of country lying east of the Rocky Mountains. These beetles 
belong to two genera, Macrobasis and Epicauta, but neither of the three 
species referred to are found in California. So far as I am aware the 
genus Macrobasis is not represented in this State, but of Epicauta and 
related genera my collection contains representatives of nearly two 
dozen species found in this State, but principally in the southern por. 
tion of it. During my recent investigating trip I met with only one 
kind of Blister-beetle, the Epicauta puncticollis Mann., a slender, wholly 
black species, which, however, was not abundant in any of the locali- 
ties visited. They were most abundant in the neighborhood of Oroville, 
in Butte County, where I found them feeding upon a low-growing 
weed, Layia glandulosa, already referred to in the chapter treating upon 
the breeding grounds of the locusts. Since the Devastating Locusts had 
bred in the same locality, as was evidenced by my finding the young of 
