382 NATUKAL HISTOKY OF HAWAII. 



fluid exuded by the insect, and was one of the conspicuous signs of the subtle 

 attacks of the troublesome bug. 



As the development of the insect from the egg to the adult is not divided 

 into definite stages, as is the ease with the buttertiy for example, the young 

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

 wings are acquired, however, by a process of moulting, and in due time the 

 insect is fully matured. The eggs, necessarily quite small are deposited along 

 the mid-rib of the leaf, or in exposed portions of the stalk. The place of 

 insertion is marked at first by a white spot with a waxy covering over the 

 opening. Four to six eggs are deposited in each 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 thev emerge from the nest and begin to feed. Thev continue to feed 

 until they develop their wrings, 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 ,iump to a 

 more secluded spot. 



Scientific study of their habits 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 by 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 seriously to worlc 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 be expected when they 

 were 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 the greater part of those produced Avere 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 turn depositing their own eggs in them in such a 

 way that the young of the parasite would feed upon and kill the eggs of the leaf- 

 hopper before they had time to develop. 



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

 into Hawaii, the species carefully studied in captivity, and the young parasites 



