20 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 



Grote's paper before the American Association for the Advancement of 

 Science, in 1874, we shall give somewhat in detail in Chapter XIY, but 

 in this connection we may appropriately devote a brief space to the 

 consideration of Mr. Grote^s arguments : ^ 



The principal arguments urged in support of the theory by Mr. Grote 

 are [1] the sudden appearance of the moth in quantities j [2] the first 

 appearance of the worms so late as the latter part of June; [3] the 

 absence of parasitic checks; [4] the highly probable exotic origin of the 

 epecies and its introduction into the States; and [5] the power of flight 

 and migratory habits of the moth. The first three lose much of their 

 force from the facts adduced in this report, since [IJ in the southern 

 portion of the belt^^ the sudden appearance is more apparent than real; 

 [2] the worms appear in April;* and [3] they have numerous parasitic 

 checks. There is also little force in the fact of original introduction 

 from some foreign country, since most of our worst insect pests that are 

 now acclimated and established with us were originally introduced from 

 abroad; while [5] the migratory habit, as we have seen, is not developed 

 in the first moths. Arguments urged by others in favor of the theory 

 are [6] the periodical visitations and intervals of immunity; [7] the short 

 life of the moth ; and [8] the failure of those who have tried to keep it 

 through the winter. 



To these it may be replied that [6] many other indigenous insects 

 abound during certain years and are unknown in others, and that these 

 changes are due to the working of well-known laws; that periodicity in 

 the appearance of Aletia is largely imaginary, because it either refers 

 only to bad years and takes no stock of small numbers, or else is local. 

 The investigations of the Commission show that the worm has been in 

 Bome parts of the South ever since the civil war, and there is no reason to 

 suppose that it was not annually to be found in fewer or larger numbers 

 prior thereto. [7] The short life of the moth of the summer generations 

 is no criterion for that of the last or hibernating brood, since any num- 

 ber of species which produce several annual generations and have but a 

 brief span of life in the imago state in summer are known to hibernate in 

 this state. [8] It is extrem ely difficult to attain, in a room, the proper con- 

 ditions of moisture and treshnessthat belong to a sylvan atmosphere, and 

 we have never been able to keep other Lepidoptera which hibernate in 

 the imago state alive through the whole winter in such artificial situation, 

 though we have tried with both Danais archippus and Faphia glycerium. 

 For this reason it will always be next to impossible to get absolute and 

 incontrovertible proof of the hibernation of Aletia by watchiug the moths 

 from fall till they oviposit in the following year, but it may be truly said 

 that if the hibernation of other species rested on equally absolute proof, 

 there is not one among the Lepidoptera, or other Orders, for that matter, 

 that could be said to hibernate. One other argument that has been 

 made in favor of the theory may lastly be mentioned. It is that during 

 the late war no cotton was grown for three years in some sections of the 



* See farther facts in Note 12. 



