21 



each side jirovided with three backward-curved l)ristles. 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 yellowand the antenn;e black with 

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

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

 greenish or yellowish; tibia; dirty yellowish, their apex and the tarsi black. 



Wingi'd migrant. — Length of body 2 to 2.4"'"'; expanse of wings 7 to 8.2"'™. Antennse 

 longer than the body, reaching to or l^eyond 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. Nectaries as usual, reaching slightly beyond 

 the end of the body, though not beyond the tip of the tail, andal)Out 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 fre<iuently 

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

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

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

 black. Antenna^ and nectaries black, the two Ijasal jointsnf the antenna:- sometimes 

 dusky. Tail either colorless, i)ail greenish, or almost yellow. Legs yellow, the 

 terminal third oi the femora, apex of the tibia>, and the tarsi black. Wings colorless, 

 the subcostaand l)ase of front wings yellow or greenish yellow. Stigma yellowish 

 or pale dusk}'. Costa and veins brown to black. 



The sexual g-encratiou has not been observed. 



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

 observed liy the writer, the following ma}^ be mentioned: 



The true parasites, ])red from this species are: Aphidivs avenwphis 

 Fitch and Aphldiux ohscuripes Ashm., Lygocerm 7iiger Howard and 

 Asaphes mdgaris Walker; while, the enemies observed to feed upon 

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

 maculata DeG., Hippodamia eonvergens Guer., glacialh Fal)., IS- 

 punctata Linn., and Coce'ineUa 9-notata Hbst, ; also larva^ of the 

 following Syrphus-flics: Si/rp/iNS ame7'icanui^ Wied., Xanthogratmna 

 emai'g'inata Sa}', AUograptit ohliqua Say, and Sj^hxrojyhoria cijllndTica 

 Sa}'; specimens were also bred of two small Muscid flies, the larvae 

 of which feed on the aphides, as Leucopris nlgrieornis Lgger and 

 Lcncopix simplex Loew. 



THE CLOVER PLANT-LOUSE. 



{Marrosi})]ium 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 1892, 

 on wheat {Triticuni vulgare)\ and on oats {Arena sativa)^ at Wooster, 

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

 appearance, I considered to l>e but a variation of the (so-called) 

 Sip/ionophora ai^eme, Thomas. During Jul}^, 1892, I found it also 

 feeding on the stems of Y(^d q\oyq.y {Trlfolium 2))"(itrn'^e)^ and during 

 Novemljer of the same j^ear on the petioles and leaves of strawberries, 



