12 Eighteenth Report State Entomologist of Minnesota — 1920 



The present tribe found its first conception in the genus Siphono- 

 phora of Koch (1855). Thomas (1879) recognized the tribe Siphono- 

 phorini of very heterogenous composition including the Myzini. 

 Sanborn (1904) and Wilson (1910) give the term Macrosiphini with 

 inclusion of the Myzini. Oestlund (1919) restricts the Macrosiphini 

 by the exclusion of the Myzini. Baker (1920) considers it as a sub- 

 tribe under the term Macrosiphina including also the Myzini. 



The present tribe has for some time been recognized as distinct 

 from the Aphidini, but more or less obscured by the inclusion of the 

 Myzini. When the Myzini are excluded the tribe stands out as one 

 sharply defined and supported by a long series of distinguishing char- 

 acters. A character of first importance is the sensilla in accordance 

 with the two previous tribes. The Macrosiphini, to be sure, have 

 apically enlarged sensilla with the Callipterina and Myzini, but here 

 they are never globate. Rather, they are spoon-like or spear-like, 

 widening at the apex, which is more or less pointed like a spear, indi- 

 cating a modified type or line of origin ; in some cases the widening of 

 the tip may not be apparent, and they are finger-like with a rounded 

 apex. We trace them from the Calaphidini, the same as the Myzini, 

 but from a dififerent stock from which they derived their distinctive 

 type of sensilla as well as other characters not found in the Myzini 

 and Aphidini. The size and type-form of the body is distinctive and 

 found again in the Calaphidini, some of which in the field would easily 

 be mistaken for a Macrosiphum if we did not notice the cornicles. 

 The legs and antennae are long and slender, the spur of the terminal 

 segment reaching its greatest length here. The secondary sensoria of 

 the spuria are very persistent and are usually found on the third seg- 

 ment, while in other tribes their presence is very exceptional. 14ie 

 cornicles are usually very long and cylindrical, sometimes wider at the 

 base, and sometimes distinctly swollen ; the reticular lines of the apical 

 part are retained verv sharp and distinct, the lines forming polygonal 

 areas or cells of various size and number. In swollen cornicles these 

 areas may be very much restricted, forming a ring just below the rim. 

 In some with comparative short cornicles, the reticulation may be 

 broken, as in the Aphidini. The cauda is also a very distinct form, 

 often referred to as the jjrincipal characteristic of the genus Macro- 

 siphum, being rather thick at the base, then somewhat suddenly nar- 

 rowed and turned upward. The narrow portion may be looked upon 

 as an extension of the original thick and blunt cauda of the Calaphi- 

 dini. The venation is very constant and uniform except in a second 

 division or subtribe where the venation is variable, inconstant, and 



