382 NATURAL HISTORY UF IIAAVAII. 



tiiiid exuded by the insect, and was one of the conspicuous si^ns of the sulitle 

 attacks of tlie troublesome bug. 



As the development of the insect from the e^'^;' to the adult is not divided 

 into definite stages, as is the case with the butterfiv for example, the young 

 when hatched resemble the adult, except they do not at first have wings. The 

 wings are accjuired, however, by a process of moulting, and in due tinu' the 

 insect is fully matured. The eggs, necessarily quite small ai'e deposited along 

 the mid-rib of the leaf, or in exposed portions of the stalk. The i)laee of 

 insertion is marked at fir.st by a white spot with a waxy covering over the 

 opening. Four to six eggs are deposited in eacli opening; moreover, several 

 clusters are deposited by a single female. 



As time passes the white spot, if occupied by living eggs, becomes claret- 

 colored. When first hatched the young are almost colorless. After some 

 effort they emerge from the nest and begin to feed. They continue to feed 

 until they develop their wings, and finally die of old age. As a rule they do 

 not fly when disturbed, but sidle to the opposite side of the leaf or jump to a 

 more secluded spot. 



Kcientifie study of their haliits shows that the first injury done to the cane 

 by them is when it is punctured for the deposition of the eggs. The puncture 

 produces a drain on. the plant's vitality and admits various diseases through 

 the wound. But the most serious injury is that done liy the young insects to 

 growing cane. 



Everything that ingenuity could devise was tried to lessen the damage 

 done by them, but without success. The seriousness of the invasion was soon 

 appreciated and scientific entomologists were speedily assembled in Hawaii, 

 and from here sent out to all promising countries to look for the most effec- 

 tive natural enemies of this insect pest, a pest that had already cost hundreds 

 of thousands of dollars in diminished returns from this important crop. When 

 the entomologists went serioiisly to work they found a number of natural ene- 

 mies of the hopper. But in choosing the most desirable and efficient one, they 

 had to consider their effectiveness, the possibility of their transportation, the 

 probability of their thriving, and the rate of increase to lie expected when they 

 w^ere once established. 



It was found for the work to be done that certain little egg parasites were 

 very promising, since they completed their life cycle every three weeks the 

 year round, and tiie greater part of those produced were females. With 

 such habits it was plain that within a very few months after the original col- 

 onies were liberated, thousands of millions of descendants of the original stock 

 would be at work searching out the spots on the cane where the leaf-hoppers 

 had deposited eggs, and in luiii depositing their own ey^s in them in such a 

 way that the young of the parasite woiUd feed upon aiul kill the eggs of the leaf- 

 hopper before they h;id time to develop. 



When the proper data had been secured, the egg parasites were imported 

 into Hawaii, the species carefully studied in captivity, and tlw .\(nuig |iarasites 



