SYNOPTICAL KEY TO THE APHIDIDAE OF MINNESOTA 129 
and specialized. The division may further be divided into two sections 
based on the number of segments with secondary sensoria : 
a. The third segment of the antennae with 12 or more sensoria; the fourth 
and usually also the fifth with a smaller number............ Section A 46 
b. Secondary sensoria present only on the third segment.......... Section B 47 
46. Section A. The third segment of the antennae with 12 or 
more sensoria more or less scattered; the fourth and usually the fifth 
with a smaller number. Usually rather large forms. The following 
species are recorded from Minnesota: 
(33) APHIS HELIANTHI Monell, 1879 
Found on Helianthus; dark green in color; when numerous cause | 
the leaves to curl. 
(34) APHIS MIDDLETONI Thomas, 1878 
Found on the roots of Erigeron canadensis and other Compositae. 
(35) APHIS THASPII Oestlund, 1887 
Found on Thaspium aurewm; abdomen dark green. 
(36) APHIS NEILLIAE Oéestlund, 1887 
Found on Ninebark, Physocarpus opulifolius; abdomen black. 
(37) “APHIS -CARDUELLA > Walsh, 1862 
Found on Circium; abdomen dull green. 
(38) APHIS NEPETAE Kaltenbach, 1843 
Found on Nepeta catarea; abdomen green. 
(39) APHIS RUMICIS Linnaeus, 1758 
Found on Rumex, Chenopodium, and other herbs; abdomen black. 
(40) APHIS MAIDIS Fitch, 1856 
Found on corn; abdomen green. 
(41) APHIS MIMULI Oestlund, 1887 
Found on Mimulus: a very small form; abdomen pale green. 
47. Section B. Secondary sensoria are found only on the third 
segment. The following species are known from Minnesota : 
(42) APHIS CARDUI Linnaeus, 1758 
Found on plum and thistle; rostrum very long for an Aphis. 
(43) APHIS RIPARIAE Oestlund, 1886 
Found on Vitis riparia, 
(44) APHIS CORNIFOLIAE Fitch, 1851 
Found on Cornus; abdomen dark brown. 
(45) APHIS OXYBAPHI Oestlund, 1887 
Found on Oxybaphus angustifolia. 
