358 



PSrCHE. 



[March i8<,6. 



Hiiber following Bonnet thought that 

 these aphid eggs consisted simply of a 

 pellicle containing a developetl aphis, 

 that " the insect in a state nearly per- 

 fect quits the body of its mother in 

 that covering which shelters it from the 

 cold in winter, and that it is not as 

 other germs are, in the egg surrounded 

 by food, by means of which it is de- 

 veloped and supported." But this is 

 erroneous, as these are true eggs, a tact 

 which has already been pointed out by 

 Lubbock and many other naturalists. 



A species of aphis living upon the 

 English Daisy was found by Sir John 

 Lubbock to deposit, in autumn, eggs 

 upon the leaf-stalks. These eggs were 

 taken by the common yellow ants to 

 their formicaries where they were 

 " tended by them with tlie utmost care 

 through the long winter montiis, laitil 

 the following March, when the young 

 aphides which hatch are brought out 

 and again jjlaced upon the young shoots 

 of the daisy." This eminent naturalist 

 adds; "This seems to me a most 

 remarkable case of prudence. Our ants 

 may not perhaps lay up food for the 

 winter ; but they do more, for they keep 

 during six montiis the eggs which will 

 enable them to procure food during tlie 

 following summer, a case of prudence 

 unexampled in the animal kingdoin." 



The instances above cited relate to 

 iiphides living upon plants outside of 

 the nests of the ants. But there are 

 certain species living underground in 

 care of the ants, whose eggs are simi- 

 larly tended. For many years an insect 

 called the Corn Root-aphis (^A. maidi- 



radicis) was destructive to Indian corn 

 in many of the western States. It was 

 found from spring to autumn upon corn 

 roots, always tended by the little Brown 

 Ant {Lasius sp.) which dug channels 

 for it and cared for it in every way. 

 The winter history of this aphis had 

 proven a decided enigma to entomolo- 

 gists. No one had been able to finil it 

 during winter in any stage. Somi- 

 years ago, while investigating this sub- 

 ject under tlie direction of Professor 

 S. A. Forbes, one day late in April, I 

 came across a mass of aphid eggs in a 

 nest of the ant just mentioned — the- 

 formicary occiuring in an old corn field 

 in central Illinois — which were carried 

 to the State Laboratory of iNatural His- 

 tory. They hatched the next day into 

 aphides that subsequently developed into 

 the species in question. Many similar 

 observations were subsequently made 

 at the conclusion of which I summar- 

 ized the life-history of the insect as 

 follows : — 



During the first warm days of spring, 

 usually before the ground is plowed, then' 

 hatch from the eggs small greenish lice thai 

 are transferred by the ants to the roots and 

 radicles of Setaria and Polygonum, where 

 they are carefully tended by the ants. In about 

 a fortnight these young have become adult 

 stem-mothers and give birth to quite a num- 

 ber of young. In the meanwhile the ground 

 has probably been plowed, and some crop 

 sowed. In case this crop is corn the ants 

 transfer the lice to the corn roots; but. if it 

 is oats or wheat they may continue to rear 

 the lice on Setaria and Polygonum. The 

 young from these stem-mothers become 

 adult in about a fortnight, and some of them 

 are apterous and others winged. The winged 



