6 



seem to me to be decidedly on the increase. Hitlilerto, our studies 

 of its life history have given us no hint of a method of control; 

 but observations made during the spring of 1886 make it seem possi- 

 ble that this destructive species may be added to the list of those 

 capable of being held in check by the ordinary processes of aii_J 

 intelligent agriculture. The early period at which the presence 

 of this insect may be detected in fields of the most various his- 

 tory, has seemed to justify the inference that its occurrence has 

 no close relation to the rotation practiced; but a long series of 

 careful observations made i^ery early, when the corn was but an 

 inch or two high, failed to discover a single instance, out of a 

 great number, in which this louse was present in fields where 

 the ground had not been in corn the year preceding. It was seen, 

 however, that the development of a winged generation may occur 

 so soon as to give opportunity for very early infection of corn on 

 stubble or sod.* 



The notorious soft maple baek louse {Pitlvinaria innumera- . 

 bilis), which so seriously injured soft maple trees in 1884, seemed 

 to the casual observer, in spring of the following year, to threaten 

 an equal injury; but upon close inspection late in June, the cottony 

 egg masses of the female were found, in nearly every instance ex- 

 amined, to harbor a coccinellid larva {HypcA'aspis) by which the 

 eggs were being rapidly devoured; and before the end of the sea- 

 son the pest was reduced to insignificance throughout the greater 

 part of the area infested by it. 



* Since the above was written, the winter history of this species has been determined, chiefly 

 by investigations n.ade, nnderniy direction, by my assistant, Mr. C. M Weed. The egA's are col- 

 lected from the ground in autumn by tlie common brown jint, Lasius alf\/'ii. Early in 

 in spring, before corn is planted, the young lice, as they hatch, are placed on the roots of "pigc^on 

 grass" iSefai id), smartweed i I'olygoi'hn,), and possibly some other weeds, and are reared there 

 until the field is planted to corn— if this is done,— when they attack the corn roots or the sub 

 terranean part of the stem. If the field is planted to some other crop, the young lice mature 

 on the grass roots and produce a second brood, many of which ac(iuire wings about the middle of 

 May, and then disperse. Later, they seem to abandon the grasses entirely. 



