THE PRACTICAL ENTOMOLOGIST. 



39 



biani, in a paper recently published, that these in- 

 dividuals at first are neither females, nor neuters, but 

 hermaphrodites. If this be so, it is the only known 

 instance of an animal, so high in the scale of the 

 creation as an insect, being of the hermaphrodite 

 sex; though several inferior Mollusks, our common 

 Snails for example, are so. As a general rule, most 

 species of Aphis produce males late in the season, 

 when copulation takes place in the usual manner, 

 and eggs are laid by the impregnated females to 

 continue the species next year. In the case of the 

 Apple-tree Plant-louse the eggs, which are minute, 

 shining, elongate-oval, black bodies, may be found 

 in the winter in large numbers glued to the twigs. 

 But in the case of the Grain Plant-louse Dr. Fitch 

 says, that "he has watched it the year round, so 

 closely, that he is perfectly assured no eggs were 

 laid and no males were produced;" and he further 

 states that in the autumn " the mature lice continu- 

 ed 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 were buried beneath the 

 snows of winter, and with the warmth of the ensu- 

 ing spring they were thawed and returned to life 

 again." {Prarrie Farmer, Nov. 8, 1862, p. 292.) 

 Mr. Cyrus Thomas also found living lice upon 

 young green fall-wheat, in South Illinois, in the 

 middle of the winter, and after much sleet and snow 

 had fallen. (^Prairie. Farjiier, Jan. 18, 1862, p. 

 35.) Nay, even so far north as Connecticut, Mr 

 Vcrrill found very numerous Woolly Plant-lice of 

 all sizes on the branches of an Apple-tree so late in 

 the year as December 11, and after "two snow- 

 storms and many cold rains and freezing nights." 

 (Practical Entomologist I, p. 21.) Except on 

 the hypothesis that in certain species of Plant-lice 

 males do not appear at all, or only appear in cer- 

 tain exceptional seasons, it seems difficult to ex- 

 plain all the above facts. Similar cases occur in 

 certain other families of Insects, for instance the 

 Gall-flies. 



After all, such calculations as those which have 

 been quoted above, of the astonishing fecundity of 

 Plant-lice, are rather matters of theoretical curiosi- 

 ty than of practical utility. In point of fact, Plant- 

 lice never do increase at anything approaching to 

 the rate established by the theory, because they 

 are always more or less checked and controlled by 

 certain causes to be hereafter explained. Thus the 

 theory is like one of those problems in Mechanics, 

 where it is assumed that a lever is perfectly inflex- 

 ible, that a rope is perfectly flexible, and that there 

 is no such thing as friction, none of which three 

 things can ever take place in actual practice; or 

 like the problem with which the schoolmen in the 

 middle ages amused themselves, namely, how many 

 thousand angels could dance on the point of a nee- 

 dle without jostling one another!' 



FRIENDS OF THE PLANT-LICE. 

 If the reader will refer once more to the figure 

 given above, he will find — besides the little projec- 

 tion at the extreme tip of the abdomen, which is 

 the ovipositor or egg-laying instrument — another 



little horn-like projection on each side of the abdo- 

 men not very far from its tip. This is called the 

 honey-tube, and through it the insect has the power 

 of secreting at will a drop of sugary fluid. If the 

 plant-lice are left to themselves, this fluid is from 

 time to time discharged upon the leaves of the in- 

 fested plant, when after drying up it forms a sweet 

 glutinous substance, well known to school-boys by 

 the name of honey-dew. Thanks to the poor de- 

 spised "bug-hunters," we now fully understand 

 the nature and origin of this "honey-dew." But 

 in olden times it puzzled philosophers dreadfully, 

 because in those times it was considered to be be- 

 neath the dignity of a philosopher, to open his eyes 

 and read for himself in the Great Book of Nature. 

 For instance, the Roman naturalist, Pliny, gravely 

 hesitates whether to call this honey-dew "the sweat 

 of the heavens, the saliva of the stars, or a liquid 

 produced by the purgation of the air." 



But in 99 cases out of a 100, the Ayhis is not 

 allowed "to waste her sweetness on the desert air." 

 Ants, as most housewives know to their cost, are 

 very fond of sweet things, and wherever you find a 

 tree or other plant infested by Aphis, there you 

 find almost invariably swarms of ants passing and 

 repassing up and down the trunk of the tree or the 

 stem of the plant. Examine closely one of the 

 groups of Plant-lice, and you will generally see one 

 or more ants walking about among them. Exam- 

 ine the group still more closely with the assistance 

 of a pocket lens, and you will from time to time 

 perceive an ant drumming gently on the back of a 

 Plant-louse with its flail-shaped antennae, till it has 

 coaxed the Plant-louse into emitting from its honey- 

 tubes a drop of sugary fluid. This the ant greedily 

 absorbs, and then passes on to another and another, 

 until having filled itself to repletion, it descends to 

 the earth and regains its nest. Here the sweet flu- 

 id is disgorged into the mouths of the helpless and 

 legless white maggots, which are the larva? of the 

 future ants, and which are entirely dependent for 

 their food upon the fostering care of these working 

 or wingless ants, the male ants, like the drone of 

 the honey-bee, being idle gentlemen, and the fe- 

 male ants, like the queen-bee, seldom leaving the 

 nest. In the words of Linnaeus, which were utter- 

 ed a century ago, though very few, except professed 

 naturalists, have heeded them up to the present 

 day, "The ant ascends the tree, that it may milk 

 its cows the Plant-lice." 



In Natural History there is scarcely a single rule 

 without its exception. The facts recounted above 

 will apply to hundreds of difierent species of Ap)his; 

 but in the case of the Grain Plant-louse {Aphis 

 aoeitse), though the honey-tubes are well developed, 

 j'ct they emit no honey; and in consequence of this 

 remarkable anomaly the species, as has been re- 

 marked by Dr. Fitch, is not attended by any ants. 

 In other words, as this peculiar breed of cows gives 

 no milk at all, the milk-maids do not think it worth 

 while to visit them. In the human species, little 

 boys and girls sometimes deceive one another into 

 mistaking an empty egg-shell for an egg full of 

 meat; and it is said that professed cock-fighters 



