22 



owing to their lively movements, about as many more escaped out of 

 the breeding vase, when from time to time I opened it in order to 

 catch them. As to their habitually living in these infested grapes, 

 the observations already made with regard to the Guest-beetle apply 

 with two-fold force, inasmuch as they were about twice as numerous 

 as the Guest-beetle. 



It is worthy of remark, as illustrating what I have called the 

 "Unity of Habits"' in the same genus of insects, that another species 

 of the same genus, the Apple Midge {Sciara [molobrus] mail. Fitch) 

 was found by Dr. Fitch to be a Guest in apples infested by the com- 

 mon Apple-worm {Carpocapsa pomonclla, Linnaeus), and to appear in 

 the Avinged state at the same inclement period of the year as my 

 Grape Midge, namely in February. 



Fruit-growers must observe carefully the important practical 

 point, that none of these Guests do them any harm. It is thi« 

 Grape Curculio, for example, that in the first instance attacks the 

 berry; and after the berry for all practical uses is ruined, the Guests 

 merely pick up the stray crumbs that fall from the Curculio's table, 

 and clear a^ay from off the face of the earth decaying vegetable mat- 

 ter, that would otherwise become putrid, unwholesome and offensive. 

 To make war upon the Guests would therefore be as irrational, as for a 

 sheep-grower to shoot the turkey-buzzards that are feeding upon tho 

 dead carcasses of his sheep, and overlook the blood-thirsty curs that 

 in the darkness of night had carried death and destruction among 

 his flocks. 



Nothing is more common among young entomologists than to 

 jump to the conclusion that, merely because they breed a certain in- 

 sect from some vegetable organism which has manifestly been de- 

 stroyed by insects, therefore the bred insect is the author of the mis- 

 chief. Xo mode of reasoning can be more unsafe and unsound. The 

 bred insect may be, and very frequently is, a Guest; and the Host, 

 Avho is the real guilty party, may be entirely unknown to them. Or, 

 what is still more common, the bred insect may be a Parasite, feeding 

 upon the body of some unknown species that had originated the dam- 

 age, and consequently not our foe but our friend. To solve satisfac- 

 torily such questions as these, requires careful and long-continued 

 observation and experiment, and an extensive familiarity with the 

 habits and peculiarities of insects. And even then the very best and 

 most careful entomologists will sometimes be led into error. For, 

 although it is a very general rule that species belonging to the samo 

 Family of Insects have the same general habits, yet every now and 

 then certain remarkal)le exceptions to the rule are brought to light. 



