April 1S01 



PSYCHE. 



61 



OEBALUS PUGNAX AN ENEMY OF GRASSES. 



BY II. GARMAN, LEXINGTON, KV. 



This is one of the commonest of the 

 Pentatomidae in Kentucky, occurring 

 everywhere in July and August on 

 grasses. Its constant presence and abun- 

 dance on millet attracted my attention 

 in 1SS9, Dut with Podisus spinosus 

 and other predaceous members of the 

 family in mind, it was assumed to be 

 there after other insects, and was not 

 given special attention. In the summer 

 of 1S90 it was again found to be 

 common on several species of Setaria 

 and Panicum, — so common that as 

 many as twenty adult bugs could be 

 taken from a single stool of grass. This 

 time the incongruity of a predaceous 

 insect congregating on particular species 

 of grasses, where there was no evident 

 animal food, made its impression, and 

 a brief examination was sufficient to 

 show that the bugs were attracted by 

 the grasses themselves, which they were 

 puncturing, and from which they were 

 extracting the sap. They seemed espec- 

 ially fond of the young spikelets, and 

 where the bugs were abundant large 

 numbers of the spikelets were found 

 to be dried up, having been emptied 

 of their contents. 



On July 16 a number of the bugs 

 were collected from Setaria glanca and 

 Panicum sangtii?tale, and confined 

 with a bunch of grass in a breeding cage, 

 where they were observed to continue 



their work of puncturing the spikelets. 

 Some individuals were coupled when 

 taken, and on the 19th of July the eggs 

 were found to have been placed in scat- 

 tered clusters of about a dozen eggs each, 

 on the stems of grass, and on the sides 

 of the cage. Each cluster consisted of 

 two series, the eggs being in contact, 

 but those of one series alternating in 

 position with those of the other. This 

 arrangement of the eggs accommodates 

 them to the stems of grasses. The habit 

 ofso arranging them appeals to be fixed, 

 for no matter where placed the double 

 lines were always adhered to. The eggs 

 are pale green, and measure .7 mm. in 

 length by .6 mm. across, the diameter 

 being maintained to the extremities. 

 The attached end is perceptibly convex. 

 The free end is so little convex as to ap- 

 pear flat; it is rimmed, and provided 

 with a marginal series of capitate ap- 

 pendages which are so small as not 

 to be easily made out even with a good 

 lens. 



From my own observations I should 

 have supposed Oe. pitgnax to be exclu • 

 sively a vegetable feeder, but in the 

 fourth report of the United States Ento- 

 mological Commission, p. 97, I find it 

 stated that the species has been observed 

 attacking the cotton worm. Of course 

 there is nothing improbable in its taking 

 both vegetable and animal food. 



