1867. 



NEW ENGLAND FARMER. 



369 



will take an interest in their business, and form an 

 attachment to the farm, which they might not do, 

 if no account were kept with the several fields, 

 crops and animals which they cultivate or produce. 



For the New England Farmer. 

 NOXIOUS ANIMALS, INCLUDING IN- 

 SECTS.— NO. VII. 

 Plant Lice. — Continued. 



Another anomaly of the Aphidians is, that 

 they are both oviparous and viviparous. The 

 perfect winged insects appear in the spring or 

 early summer, and again in autumn ; the fe- 

 males, sometimes wingless, then laying eggs, 

 from which is hatched a generation of wingless 

 lice, apparently of one sex only, and generally 

 called females, which are viviparous without 

 the interposition of males, bringing forth a 

 numerous progeny like themselves, which in 

 turn bring forth another like progeny, and so 

 on, to the seventh or eighth generation before 

 the winged males and egg-laying females again 

 appear. 



In regard to this singular manner of repro- 

 duction, Prof. Walsh, of the Practical Ento- 

 mologist, says: "How under these circum- 

 stances the process of generation is accom- 

 plished, is a curious, and at present, an un- 

 settled problem. Some distinguished German 

 Entomologists maintain that these so called 

 females are neuter {Ammen,) without any 

 regular ovaries developed, and that it is by a 

 sort of budding process, analogous to that of 

 the Polyps, that the young plant lice are de- 

 veloped within the parent stock. I have just 

 heard from Mr. Darwin that it has been de- 

 monstrated by Balbiani, in a paper recently 

 published, that these individuals at first are 

 neither females nor neuter, but hermaphrodites. 

 If this be so, it is the only known instance of 

 an animal, so high in the scale of creation as 

 an insect, being of the hermaphrodite sex." 



In the zoology of Agassiz and Gould another 

 theory is noticed, — that the so-called interme- 

 diate females are not parents, by budding or 

 otherwise, but nurses, preserving in their own 

 bodies, and committing to the bodies of their 

 successors the offspring of their ancestors. 



The well known fecundity of plant lice has 

 been the basis of some curious calculations in 

 regard to their possible increase in a given 

 time, and under favorable circumstances. 

 Fortunately for us, such circumstances do not 

 often concur, so as to make their theoretical 

 increase pi-actical ; yet their actual increase is 

 sometimes astonishing. The year 1861 must 

 have been highl}- favorable to the oat louse — 

 before described as of a reddish brown color, 

 called also the grain louse, because it is found 

 on wheat, rye, oats, barley and to some extent 

 on Indian corn. In that year they appeared 

 in multitudes which no man could number, 

 simultaneously throughout New England and 

 some of the Middle States, damaging more 

 especially late spring grain. Just before an 



acre of wheat, belonging to the writer, began 

 to ripen in that year, it was estimated from a 

 careful examination and several countings, 

 that the number of plant lice infesting that 

 crop was equal at least to one-half of the 

 number of grains of wheat. The product of 

 the acre was eighteen bushels, and allowing 

 seven hundred and sixty-eight thousand grains 

 to the bushel, there were nearly seven million 

 of lice. Yet this large number is not one- 

 eight-hundredth part of the possible theoreti- 

 cal number of the fifth generation from a single 

 progenitor, according to Reaumur. Or, in 

 other words, a single female Ajjliis, on this 

 theory, might be the parent of a iifth genera- 

 tion sufficiently numerous to stock more than 

 eight hundred acres, with one louse to every 

 two grains of wheat. And as this species ma- 

 tures very rapidly, and the generations succeed 

 each other at short intervals, all this vast in- 

 crease might take place in a few weeks. Prac- 

 tically no such increase ever takes place, yet 

 the progenitors of the myriads of lice that in- 

 fested the grain of 1861 were so few that 

 neither they nor their offspring were generally 

 noticed until after the heading of the grain. 



Among these grain lice no winged or per- 

 fect insects were discovered, although such are 

 always found on the apple tree in the early 

 part of the season. This absence of the per- 

 fect insect I supposed to be due to the time of 

 observation — it being too late for the winged 

 lice of spring, and too early for the winged 

 lice of autumn. But it is stated in the Janu- 

 ary number of the Practical Entomologist that 

 Dr. Fitch, who carefully watched this Aphis 

 the year round, failed to find any eggs, or egg- 

 laying lice. So that this species not only ex- 

 cels in fecundity, but is even more mysterious 

 than other species in its manner of reproduc- 

 tion. It was also noticeable that these lice 

 were not attended by their usual friend, the 

 ant. The reason for this non-appearance, I 

 now learn from the same authority, is that this 

 species excretes no sugar or sugary fluid. 



The vast number of grain lice in 1861, and 

 their paucity in previous and succeeding years, 

 cannot be accounted for on any theory of the 

 presence or absence of pai'asitic insects, or any 

 other theory that has as yet been suggested. 



Being curious to know what would become 

 of this host of little animals when the grain 

 reached maturity, I closely watched them from 

 day to day, and brought several stalks into the 

 house, from which stalks, as soon as dry, every 

 louse dropped and perished, without making 

 any provision for a future race ; and apparently, 

 so did it happen in the field ; for when the 

 grain matured not a louse or egg could be 

 found. 



Mysterious creatures — they came — they per- 

 ished, and left no record from which to unfold 

 the secret of their mission. They did not 

 seem to be sent, like the locust or army worm, 

 as a rebuke for man's transgressions, nor like 

 quails to rebellious Israel, to be food for 



