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366 



THE ILLINOIS FARMER. 



Dec. 



ted upon tbe heads — evidently because thejuices 

 ■vrhich the p'ant elaborat s for the growth of its 

 flowers and seeds are much more nutricious, more 

 dainty and palatable to these insects, than are 

 the juices which circulate in the leaves and 

 stalks. They here fix themselves upon the base 

 of the chaffs which envelop the kernels, and in- 

 serting their beaks, they suck out the juices 

 ■which should go, first, to grow the flowers, and 

 after that to fill and perfect the kernels. And 

 now, the young lice which are born, instead of 

 scattering themselves and traveling away, settle 

 down cloHely around their parent, crowding as 

 compactly together as they can stow themselves. 

 Thus it comes to pass, that when these insects 

 are numerous, as Te have recently had them, in 

 many of our grain fields, scarcely an ear can be 

 found which has not a cluster of these lice around 

 the ba=e of almost every kei'nel, all v.-ith their 

 liny bills inserted therein, pumping out thejuices 

 ■«Lich should go to swell and perfect tho seed. 

 Thus, this grain aphis from being a solitary in- 

 sect, wandering about singly upon the leaves and 

 stalks, becomes a gregarious insect, clustered 

 together in flock?, and remaiuing fixed station- 

 ary upon the lower or butt ends of the kernels. 



At the same time another change, equally re- 

 markable, takes places in the color of these in- 

 sects. &a long as they rourish themselves on 

 the coarse juices of the stalks and leaves, and 

 leaves, their bodies are all of a grass-green color. 

 But when they come to feed on the more delicate 

 juices of the flowers, they begin to bear young of 

 an orange color. One of the grass green insects 

 having stationed herself at the base of a kernel, 

 the next day, in the group of little ones around 

 her, a yellow one will occur, all the others being 

 green like their parent. A day or two later, as 

 the nourishment she derives from the leaves be- 

 comes dissipated from her body and replaced by 

 that now obtained from the kernels, half the 

 young she produces will be of this yellow color. 

 And still later, all the young are yellow, no green 

 ones being any longer born. And the older ones 

 after a time dying and disappearing, all these in- 

 sects some weeks before harvest time, become 

 changed to a yellow color, their hue inclining 

 more to red in some and to yellow in others. 



It is truly curious that this green insect, thus, 

 on coming to feed on thejuices which grow the 

 flower?, begin to produce young of a gay yellow 

 color similar to that of the flowers. 



Cy depi'iviug the kernels of a portion of the 

 milky juice which should go to swell and mature 

 them, this insect causes the ripened grain to be 

 more or less shrunken and light of weight. 



Rye, however, grows so rapidly and ripens so 

 early, that it outstrips this aphis in its increase, 

 and thus sustains no material injury from it. 

 Winter wheat, ripening more slowly, experiences 

 more injury. But the crops -which ripen the 

 latest, and when this aphis has become multipli- 

 ed to the greatest extent, namely, spring wheat 

 and oats, become the most thronged and sustain 

 the greatest injury. 



Let us next inquire how it is that this insect 

 is able to become so suddenly and so excessively 

 multiplied as we have had it, in the Eastern part 

 of our State last year, and here in its Western 

 part this year. 



I may observe that a hundred years ago it was 

 a current opinion among men of science, that 

 certain insects and other creatures pertaining to 

 the lower orders of the kingdom were generated 

 spontaneously. But more recently, when these 

 instances of supposed spontaneous generation 

 came to be clesely investigated, one after another 

 of them were found not to be such. So that at 

 this day the scientific world wholly discards the 

 theory that there is or can be any such thing as 

 spontaneous generation. All living things de- 

 scend from parents ; and it is by a pairing of the 

 sexes that young arc produced and that each 

 species is continued in existence — some classes of 

 animals bringing forth their young hatch. 



Insects are of this latter kind. They are all 

 produced from eggs. But in the generation of 

 the plant lice, we meet with one of the most re- 

 markable anomalies which we anywhere find in 

 the works of nature. These insects bring forth 

 their young alive, at one time, and they lay eggs 

 at another time. All the plant lice which we 

 see upon our fruit trees during the spring and 

 suDimer are females, and these do not produce 

 eggs, but living young, which nature, in a few 

 days, and (wonderful to tell !) they are fertile, 

 without any intercourse of the sexes. It is only 

 when cold weather and frosty nights arrive, that 

 males are produced. The insects then pair, and 

 the females thereupon lay eggs. The eggs re- 

 main through the winter, to be hatched by the 

 warmth of the following spring The young from 

 these eggs grow up and commence bearing living 

 young, no males and no eggs being produced, 

 except as the closing act of their operations in 

 autumn. 



Such are the general facts with regard to the 

 generation of the insects of this aphis group. 

 And I had supposed it would be the same with 

 this grain aphis. Some of you may have been 

 present and heard the remarks which I made on 

 this subject at our Fair at Water town a year 

 ago. I stated that the eggs of this insect would 

 probably be found late in autumn, scattered 

 about upon the leaves of the fall sowed wheat and 

 rye — which eggs would hatch with the warmth 

 of the following spring, to start the insect upon 

 the grain again this year. But when frosty 

 nights arrived last autumn, and when the aphis 

 on the apple trees was found paired, and the 

 females were busy depositing their eggs, to my 

 surprise nothing of this kind occurred with this 

 aphis upon the grain. The mature lice continued 

 to produce young ones, until they and their 

 young became congealed upon the leaves of the 

 young grain by the advancing cold of the season. 

 And in this state they Tvere buried beneath the 

 snows of winter, and with the warmth of the en" 

 suing spring they were thawed, and returned to 

 life again. 



To be better assured upon the subject, I placed 

 some of these insects on grain growing in flower- 

 pots and kept during the winter in a warm room. 

 In this situation they continued alive and con- 

 tinued to bear young through the whole winter 

 season. 



Thus I have watched this grain aphis this 

 year round, so closely, that I am perfectly as- 

 sured no eggs were laid and no males were pro- 



