306 STATE HORTICULTURAL SOCIETY. 



perennials, and probably it is to these plants that the true sexed indi- 

 viduals resort, in the fall, to place the fertilized eggs by which the 

 vitality of the species is annually renewed. The young lice hatch from 

 these eggs in the spring, and, after attaining their growth, begin the 

 agamic reproduction process, which goes on for a number of weeks 

 and finally develops a brood of the winged form. These desert their 

 spring feeding ground and, guided by instinct, find their way to the 

 plants upon whose juices they feast daring midsummer. 



Nature has already some checks upon the undue multiplication 

 of this species. Ladybird and syrphus fly larvae are found in large 

 numbers preying upon the lice, and the latter are also often parasited 

 by a minute chalcid. But, so far, these friends of the horticulturist 

 have not been adequate to the task of clearing the leaves of the pest. 

 The general character of the season too has a bearing on their num- 

 bers and destructiveuess. Prof. Smith has observed that cold, wet 

 springs retard their development, and that heavy rains and gales oc- 

 curring late in June, about the time that the winged brood migrates to 

 the melon vines, beat to the ground or sweep away such a large pro- 

 portion of the insects that the vines enjoy for the season a comparative 

 immunity from attack. 



As to direct remedies, the principal difliculty is to bring them in 

 contact with the insects on the under sides of the leaves which lie so 

 close to the earth. This requires the time of two persons, one to lift 

 the vines while the other applies the insecticide. The plants should 

 be frequently and critically examined early in July and the aphids 

 headed off upon their first appearance. 



In experiments on a small scale I have found the insects easy to 

 kill with equal parts of pyrothrum powder and air-slacked lime, or 

 with the preparation of tobacco and creosote sold as " X. O. dust." 

 Tobacco tea and kerosene emulsion are the most effective liquid appli- 

 cation!?. Prof. Smith made some interesting and successful experi- 

 ments with the fumes of bi-sulphide of carbon, evaporating it under 

 wooden bowls, tubs or boxes that had been placed over the plants, 

 using about two teaspoonfuls of the chemical ( which must be poured 

 in some small receptacle and not on the ground ) to each plant. An 

 exposure of an hour was sufficient to kill the lice without serious in- 

 jury to the plants. The poisonous and inflamable character of the bi- 

 sulphide necessitates great care in the handling. 



