228 INSECTS AFFECTING VEGETATION 



the cane continues and the new leaves unfold toward the top of the 

 plant, the infested leaves naturally occupy the lower position on the 

 stalk. The leafhopper, during a heavy infestation, will continue 

 to puncture the midribs of the leaves as rapidly as the leaves unfold. 

 The eggs deposited in cane growing in rearing cages hatch two weeks 

 thereafter. The period of development of the young to the adult re- 

 quires 34 additional days, making the life cycle 48 days in length. 



The fact that the eggs will hatch from cane cuttings during a 

 period of at least 38 days is a very important point to bear in mind 

 in the shipping of infested cane from one locality or country to 

 another. On issuing from the cavity, or chamber, the young, new r ly 

 hatched leafhoppers appear at first small, slim, wingless nymphs, 

 almost transparent. They are at once active and scatter over the 

 plant to feed, congregating at first down within the sheaths of the 

 upper leaves. In a few hours the body becomes shortened and the 

 outer covering, on exposure to the air, becomes darker in color. The 

 habit of the very young in secluding themselves within the lower 

 sheaths of the leaves renders them quite inconspicuous unless espe- 

 cially sought for. 



The presence of the pests on the plantations was noticed first by 

 the appearance of a sooty black covering on the lower leaves of the 

 cane plant. This black covering became known as smut. It is a 

 fungous growth and finds a medium for development in the trans- 

 parent, sticky fluid secreted by the leafhoppers during their feeding 

 on the plant. This secretion is commonly known as honeydew. The 

 black smut or fungous growth in the honeydew secretion of the leaf- 

 hopper and the red discoloration about the openings to the egg cham- 

 bers in the midribs of the leaves are the most pronounced symptoms 

 of the w r ork of the leafhopper on cane. 



In the case of heavy infestation a further result is the appear- 

 ance of the plant as a whole. The leaves on which the insects have 

 been feeding develop a yellowish appearance, and as the work of the 

 insects progresses they become dried and resemble the fully matured 

 lower leaves of the plant. This premature death of the leaves is due 

 to the excessive amount of juice extracted for food. As long as the 

 cane plant is able to produce new leaves its life is not actually in 

 danger, the injury being a check to the growth and indicated by the 

 small, shortened joints in the stalk. Leaves thus prematurely ripened 

 do not drop away from the stalk at the junction of the sheath, as is 

 the case under normal conditions, but break and hang down at the 

 junction of the leaf to the sheath, leaving the sheath still wrapped 

 about the stalk. Leaves in such a condition remain green for some 

 time, attached to the sheath by the midrib, and an attempt to strip 

 the cane results in leaving the sheaths still adhering to the stalk and 

 wrapped about it. 



In the last stages of an attack, when the plant is actually over- 

 come by the pest, the young unfolded leaves at the top do not appear 

 to have the vitality to unfold and the bud gradually dies out. At 

 this stage the normal growth of the plant ceases. Many plants in 

 such a condition will then throw out sprouts from the eyes. This is 



