36 Annals Entomological Society of America [Vol.11, 



The Tulip-tree Aphid. 

 {Macrosiphiim liriodendri Monell, and var. rufa Monell.) 



Macrosiphum liriodendri is not an uncommon species in Illi- 

 nois, occurring on Liriodendron ttilipifera, and has been observed 

 in the vicinity of Urbana for the past two years. 



It was first described by Mr. J. T. Monell from Missouri, and 

 has since been reported from Washington, D. C, by Dr. L. O. 

 Howard, who noted that the eggs were common in the pupal shells 

 of Cicada which were attached to the tree trunks. 



In Illinois, the eggs, which were first found the middle of Octo- 

 ber (1907), are laid in crevices, usually between the buds and the 

 branch. The following spring the eggs began to hatch between 

 March 29 and April 3, the young at this latter date being of the 

 first instar. The entire yearly cycle is passed on the tulip tree. 



The variety riifa Monell was first obser\^ed July 6, inter- 

 mixed with the normal form in colonies and about equaling the 

 latter in abundance. 



DESCRIPTIONS. 



Winged viviparous female: — The original description by Monell* is suffi- 

 ciently complete except for a few minor points, but owing to the fact that this is 

 the only description published of the tulip tree aphid, and that it is inaccessible 

 to many workers, I will redescribe it from Illinois specimens. 



Head pale greenish yellow or dusky; with conspicuous frontal antennal 

 tubercles, and the median ocellus projecting beyond the fore margin. (PI. VI, 

 fig. 21.) Antenna black excepting the two basal segments, which are dusky 

 green; 14-18, circular sensoria in a row on III, the usual conspicuous one at the 

 distal end of V, and one large one with several smaller ones surrounding it at 

 the apex of base VI; more than one half longer than the body. III, IV and V 

 subequal, but III always slightly longer than either IV or V, VI the longest, 

 being nearly twice V, base VI about one fourth the length of V, filament VI 

 long and setaceous. (PI. VI, fig. 22.) Eyes black. Ocelli dark red and rather 

 conspicuous. Beak barely reaching the coxte of the second pair of legs. Thorax 

 brownish. Wings hyaline with dark brown veins, the first and second discoidals 

 branching at a distance less than one half from the margin to where the third 

 discoidal branches. (PI. VI, fig. 23.) Legs black, excepting the basal four 

 fifths of the femora, which portion is pale greenish. Abdomen pale green. 

 Cornicles black excepting the extreme base, which is pale greenish; reaching 

 beyond the tip of the abdoinen, and three to three and one half times the length 

 of the style; slightly incrassated at the base and barely noticeably dilated near 

 the apex; distal end distinctly imbricated. (PI. V, fig. 17.) Style pale green- 

 ish vellow, ensiform, decidedlv uncurved, and about one half longer than the 

 hind tarsus. (PI. V, fig. 18.) " 



Measurements [from five specimens mounted in balsam] : — Length of body, 

 2 25 mm.; width, 0.77 mm.; length of wing, 3.0.5 mm.; width, 1.18 mm.; ex- 

 panse, 7.50 mm.; antenna, I, 0.135; II, 0.07; III, 0.G4-0.82, av. 0.74; IV, 0.66- 

 0.77, av. 0.705; V, 0.70-0.74, av. 0.715; VI, base, 0.175; VI, filament, 1.09-1.26, 

 av. 1.17; average total, 3.70 mm.; cornicles, 0.85 mm.; style, 0.26 mm.; hind 

 taruss, 0.16 mm. 



* Notes on the Aphididcs of the United States, with descriptions of species 

 occurring west of the Mississippi. U. S. Gcol. and Geog. Survev of the Terri- 

 tories, Vol. V, No. 1, pt. II, p. 20, 1879. 



