166 TRANSACTIONS OF THE ILLINOIS 



this is from the first, nearly parallel with the second vein, very slightlj- 

 farther from it at its tip than at its base, its fork given off forward of 

 its middle, and this fork (?) sending off the second one beyond its 

 middle. Tip of the first fork twice as far from the tip of the third 

 vein as from the second fork. Fourth vein strongly curved through 

 two-thirds of its length and then straight and parallel with the second 

 fork, its tip nearer the tip of the second fork than this is to the first 

 fork, and almost twice as far from the tip of the rib-vein as from the 

 second fork." 



Dr. Fitch inadvertently states the first fork or branch of the third 

 vein "sends off the second one;" it is the continuation of the third vein 

 that sends off the second fork, as in all other species of this genus. The 

 raised black spots on the thorax are very distinct. 



In the spring, before the heads are formed on the grain stalk, they 

 live snugly scattered over the leaves and stalks, the young lice as soon as 

 they are born wandering away from their parents without any apparent 

 disposition to form colonies. But as soon as the heads begin to appear, 

 these insects, led by a mysterious instinct, forsake all other parts of the 

 plant and congregate upon the heads, fixing themselves, head downwards, 

 upon the base of the chaff which envelops the kernel. Now the young 

 lice, instead of wandering away, fix tliemselves in compact colonies 

 around their parents. This change in habit, it is asserted, is accompa- 

 nied by a change in color, that while feeding on the leaves they are 

 grassy green, but when they change to the heads they gradually acquire 

 an orange color, and ultimately change to the colors mentioned. 



But so far as those found on the leaves and stalks are concerned the 

 description given does not appear to be uniform, for I find upon the 

 wheat this winter, and have now (Dec. i6) before me living specimens, 

 winged and apterous. The apterous specimens are more or less brownish, 

 thus agreeing with the characters given by Curtis. The only winged 

 specimen before me agrees with Dr. Fitch's description, except that the 

 head is shining black; the antennae nearly as long as the body, not pale 

 at the base; the front of the thorax greenish-yellow, back of the thorax 

 black, rest greenish-yellow; honey-tubes do not quite reach the tip of the 

 abdomen ; wings perfectly pellucid ; the rib-vein a nearly transparent 

 honey yellow, rest of the veins colorless. The arrangement of the veins 

 corresponds with that given, with the correction heretofore mentioned ; 

 the abdomen greenish-yellow, slightly flecked with fuscous in addition to 

 the lateral spots. 



But this is, undoubtedly, the species now under consideration, as is 

 shown by the form of the head and thorax, the oval elevated spots on the 

 thorax, venation of the wings, and other undoubted characters. This 

 identification, which fortunately I am now able to make, enables me to 

 add something to the history of the species. When the winter wheat 

 appears above the ground in the fall, it passes from its hiding place at 

 this time, wherever that may be, probably in the same way that it does 

 from the winter wheat to the spring wheat and oats in the spring, that is 

 by the winged individuals. 



