THE STATE ENTOMOLOGIST. 91 



conservative members, hesitated about discarding it for fear that such 

 action would bring about the very result which it was intended to 

 avoid, i e., the spread of the insect on toother and more valuable 

 varieties. In other words they feared that by taking away the Clin- 

 ton, the lice which now prefer this variety and flourish and multiply 

 upon it, would be forced to attack other varieties. They looked upon . 

 the Clinton, as a protector to the better kinds, by drawing the lice 

 away from them, arguing, to parady the words of Shakespeare, that 



" 'Tia better far, to bear those ills we have 

 Than fly to others that we know not of." 



Now while I admire the cautious spirit manifested in such an 

 argument and admit that it seems plausible, I cannot believe there 

 is any logic in it. The argument presupposes that the louse, as a species, 

 can suddenly change its habits and tastes when forced to do so ; but 

 to my mind, a new habit is not generally acquired in a species by the 

 simultaneous change of all the individuals composing it, but by some 

 aberrant individual first taking on the new habit, and transmitting 

 that habit to its descendants until a new race is in time produced. A 

 single Clinton vine may stand in the midst of a vineyard of Concords 

 for years, and, as we know to be the case, may be badly infested with 

 this louse without its spreading on to the surrounding Concords. The 

 lice may, and perhaps do, year after year spread on to and settle on 

 the comparatively tougher leaves of such Concords, but year after 

 3 T ear they perish from incapacity to sustain themselves. Someday, 

 however, one or more aberrant individuals, may, by some slight consti- 

 tutional difference from the normal type, be enabled to sustain them- 

 selves on the Concord leaves, and, by the laws of inheritance, trans- 

 mit their characteristics to their descendants until, by the survival of 

 those from each generation best fitted to flourish on these leaves, a 

 new Concord-feeding race will be produced. Therefore, as already 

 stated, I believe that there is danger of this louse spreading on to 

 other varieties, and especially on to such as are more closely allied to 

 the Cordifolia, or, to use a common but inexact expression, that have 

 Gordifolia "blood" in them. But it must not be forgotten that we are 

 here only supposing, from analogy, what may occur, because we know 

 not positively that it will occur, and it is very obvious that even if 

 there is this danger the chances of such an occurrence will be far 

 greater as long as the Clinton is allowed to grow in the vineyard, than 

 when it is uprooted and banished ; and so far as all experience goes, 

 we can safely conclude that to destroy all those vines in a vineyard 

 that are infested with this louse, is to banish it from such a vineyard 

 so that it will in future confine its attacks to the wild frost, as it did in 

 the beginning. 



The Apple-maggot (Trypeta pomonella, Walsh), as Mr. Walsh has 

 demonstrated,* is an indigenous American insect and breeds in our 



^Report as Acting State Entomologist of Illinois, pp. 29-30. 



