82 STATE HORTICULTURAL SOCIETY. 



tively insignificant, were it not for the almost marvelous rapidity with which 

 they generate. A single individual is soon surrounded by hundreds, and in 

 much less time these hundreds become thousands. In the summer season all 

 the Aphides seem to be females, and these have the power of organic repro- 

 duction. They do not pass through transformations, as most other insects, 

 though they frequently shed their skin as they increase in size. The young, 

 however, are in all respects similar to the full-grown insect, except that some of 

 the latter develop wings, a peculiarity found only in the imago. On this ac- 

 count the whole life of the Aphis seems to be devoted to imbibing sap and pro- 

 ducing its young. 



The following concise statement concerning the reproduction of the Aphis 

 copied from a paper prepared by Dr. Cyrus Thomas of Illinois: 



" In the autumn, as a general and almost universal rule, the last brood con- 

 sists of winged specimens, both males and females. These pair, soon after 

 which the male dies. Early in spring, as soon as the sap begins to flow, these 

 eggs hatch, and the young lice at once insert their tiny beaks into the bark or 

 leaf on which they are situated, and begin to pump up the sap. They wander 

 but little, their entire time being devoted to feeding; hence they grow rapidly 

 and soon come to maturity. This spring brood consists, generally without an 

 exception, of females without wings. These females, by some strange pro- 

 vision of na ure, are capable of reproducing their kind without the intervention 

 of males, and, instead of depositing eggs, as the last fall brood, are usually 

 viviparous, bringing forth living larvae These are likewise all females, similar 

 to those from which they sprang, and they in turn produce a similar brood in 

 the same anomalous manner. This process is repeated again and again during 

 the summer, and until in the fall, through some six or seven or even more gen- 

 erations. The last fall brood presents a iemarkable change, for it usually con- 

 sists almost entirely of males and females which acquire wings. These winged 

 females, as previously stated, after pairing, deposit eggs which remain over the 

 winter." 



But if the Aphis increases rapidly it is consoling to know that its life upon 

 out-door vegetation is exceedingly short, and that it disappears almost as suddenly 

 as it comes. Its plump, succulent bo ly makes it a favorite food for the larva? 

 of various, insects ; and it is a rare thing to find a plant covered with lice upon 

 which you cannot find some of these Aphis-eating larvae. One of the most 

 common of these is the syrphus fly larvae. This fly lays its eggs 

 upon plants infested by lice, and as soon as the young larva escapes 

 from its shell it begins its work of destruction ; and it is surprising 

 how many lice it can dispose of in a short time. It seems to be feed- 

 ing constantly, and as soon as one insect is eaten it takes another. 

 In this way one of these larvae will soon destroy a whole colony of 

 Aphides. 



Plant lice have many other enemies of the insect class. These are 

 mostly members of the orders Coleoptera, Diptera, Hymenoptera and 

 Neuroptera. Many of these are small insects which lay their eggs 

 just beneath the tender skin of the plant lice. As the young maggots 

 hatch they live upon the juices of their host, until at last, the body 

 Lifr^of absorbed and the larvae fully grown they pupate, soon to emerge into 

 Syrphus the f ull-fledged imago, ready to renew the course of generation. A twig 

 containing plant lice placed in a glass jar, and kept covered with a piece 

 of cloth, will soon show a variety of insects which have developed from the 

 larvae and pupae which found lodgment within the bodies of the Aphides. 



