INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 209 



When once established in a field of growing grain it is practically 

 impossible to stop its ravages, but it may be partially kept from migrat- 

 ing to cornfields by making a dust furrow or a line of coal tar around 

 the edges of the field, over which the insects are unable to pass. In 

 the dust furrow the edge next to the field must be steep and covered 

 with fine dust, which makes it impossible for the bugs to get a foothold 

 in attempting to ascend the wall. Occasionally a deep hole should be 

 sunk in the furrow, into which large numbers of the bugs will fall, or 

 they may be killed in the furrows with a drag or an oil spray. 



The application of an oil emulsion to infested corn is claimed to give 

 some relief if the work is thoroughly done. 



Natural Enemies.— A fungous disease attacks the chinch bug dur- 

 ing wet weather, and while it dors great execution it is not an important 

 controlling factor. 



THE DARK TRIPHLEPS" 



Triphleps tristicolor White (Family Anthocoridae) 



(Fig. 183) 



Description. —This is a very small species, the adults averaging 

 only about ^ inch in length. The color is jet black with the exception 



of the bases and tips of the wings, 

 which are white. When the wings 

 are folded there appear to be 

 three triangular white spots on 

 the dorsum. The antenna 1 and 

 portions of the legs are also very 

 light in color. 



Life History. — Little is known 

 relative to the life history of this 

 species, except that it appears to 

 be only predaceous upon small in- 

 sects and mites and is quite abun- 

 dant throughout the summer. A 

 closely related species, Triphleps 



Fig. 183. — The dark Triphleps, Triphleps . .,: a e ,-, tx/iwiji^ 



tristicolor White. Adults enlarged four ITISKUOSUS Say, 0± the Middle 



times. (Original) States is recorded as sometimes 



injurious to plants, but there are as yet no such records of the Cali- 

 fornia species. 



Nature of Work. — The beak is exceedingly sharp and is used to 

 pierce the prey and extract the juices from the bodies. 



Distribution. — This species is widely distributed throughout the 

 State. 



Hosts. — The writer has collected the adults from plants infested 

 with thrips, plant lice and mites upon which they appear to feed. Of 

 the plant lice and thrips only the smaller ones become prey, while prac- 

 tically all stages of the mites are attacked. 



'"This species generally replaces the insidious plant-bug, Triphleps insidiosus Say, 

 which does not appear to occur in this State. 



14— 136G4 



