21 



each side provided with three backward-curved bristles. General color a somewhat 

 polished green with a yellowish tinge along the dorsum and with a few irregular 

 darker green markings. The head is rather dark yellow and the antennae black with 

 the two basal joints brownish or somewhat dusky. Eyes dark brown. Xectaries 

 black, the tail dirty yellowish. Terminal half of femora black, the basal part pale 

 greenish or yellowish; tibise dirty yellowish, their apes and the tarsi black. 



Winged migrant. — Length of body 2 to 2.4 mm ; expanse of winga 7 to 8.2 mm . Antennae 

 longer than the body, reaching to or beyond the tip of the tail; joint 3 shorter than 

 the sixth and provided with 4 to 12 circular and elevated sensoria along the basal 

 half. Hairs minute, sparse, and simple. Xectaries as usual, reaching slightly beyond 

 the end of the body, though not beyond the tip of the tail, and about one-third longer 

 than the tail. 



Color of the abdomen green or yellowish green, the median line generally of a 

 darker shade. Head light brown or pale dusky; eyes reddish to dark brown; 

 ocelli clear, with the inner margin black. Prothorax greenish yellow and frequently 

 marked each side with a dusky impression of three more or less distinct, dusky, 

 longitudinal stripes. The mesothorax and metathorax are generally yellow, with 

 the lobes, the sternal plate, and lateral spot in front of anterior wings brown or, rarely, 

 black. Antennae and nectaries black, the two basal joints of the antennae sometimes 

 dusky. Tail either colorless, pail greenish, or almost yellow. Legs yellow, the 

 terminal third of the femora, apex of the tibiae, and the tarsi black. Wings colorless, 

 the subcosta and base of front wings yellow or greenish yellow. Stigma yellowish 

 or pale dusky. Costa and veins brown to black. 



The sexual generation has not been observed. 



Of the enemies and parasites preying on this species which have been 

 observed by the writer, the following- may be mentioned: 



The true parasites, bred from this species are: Aphidvus avenaphis 

 Fitch and Aphidius obscuripes Ashm., Lygocerus niger Howard and 

 Asaphes vulgaris Walker; while the enemies observed to feed upon 

 this plant-louse are the following ladybirds and their larva?: Megilla 

 maculata DeG. . Hippodamia convergent Guer., glacial is Fab.. 13- 

 punctata Linn., and Ooccinella 9-notata Hbst. ; also larva? of the 

 following Syrptms-flies: Syrphus americanus Wied., Xanthogramma 

 emarginata Say. AUograpta obliqua Say, and Sphmrophoria cylindrica 

 Say; specimens were also bred of two small Muscid flies, the larva? 

 of which feed on the aphides, as Zeucopis nigricornis logger and 

 Zeucopis simplex Loew. 



THE CLOVER PLANT-EOUSE. 

 (Macrosiphum trifolii n. sp. — Fig. 4.) 



Specimens of this new species have been occasionally found at 

 Washington, D. C, since the fall of 1889 until the summer of lS92 r 

 on wheat {Triticum vulgare); and on oats (Avena sat hut)* at Wooster, 

 Ohio, which, at the tuue, on account of their food plant and general 

 appearance, I considered to be but a variation of the (so-called) 

 SiphonopTwra avenaz Thomas. During July. 1892, I found it also 

 feeding on the stems of red clover (Trifolium pratense), and during 

 November of the same year on the petioles and leaves of strawberries. 



