136 PROCEEDINGS OF THIRTY-THIRD FRUIT-GROWERS ? CONVENTION. 



made to defoliating them on, this account, but only in a few cases was 

 much difficulty met with. 



In outlining our campaign, the first step in the work was to carefully 

 consider the life history of the insect— to discover its most vulnerable 

 point of attack. 



The life of the insect is divided into four distinct stages: first, the 

 egg stage ; second, the larval stage ; third, the pupal stage.; and, fourth, 

 the adult or winged stage. The flies pair very soon after emergence," 

 and the females generally begin depositing eggs in from twelve to 

 thirty hours ; they seem to prefer the under side of the very young and 

 tender leaves, except jn cases of very bad infestation, when the old 

 leaves are also covered. Writers differ on the number of eggs deposited 

 by each female, but they seem to agree on from twenty-five to seventy- 

 five as the limit, warm weather being conducive to prolific oviposit) on 

 and cold weather the reverse. The eggs hatch in from three to twenty 

 days, depending upon the temperature ; however, a large percentage of 

 the eggs are unfertile. The young when hatched somewhat resemble 

 the young of a scale insect (Coccidae) , and crawl around for a few 

 hours before they settle, which consists of inserting the mouth parts into 

 the leaf and the secretion of sufficient wax to fill the space between the 

 insect and the leaf. It now becomes a fixed form, until after passing 

 through the last stages of the nymph form, where wings are formed in 

 both sexes and the entire structure of the insect changes or undergoes a 

 molt and the delicate white fly emerges, leaving the molt attached to the 

 leaf, which is quite conspicuous. In normal conditions the insect will 

 pupate in from twenty to thirty days, and the mature fly will issue in 

 from ten to thirty days thereafter, making the time of one brood from 

 egg to adult about forty or fifty days in summer to six months in 

 winter. While the life of an individual adult fly is very short, being 

 from three days to a week, according to various writers, many mature 

 flies were kept in confinement alive for twelve days in some of our 

 experiments. The first brood appears in the spring in large numbers 

 and are present for a couple of weeks, then suddenly disappear after 

 laying their eggs. This brood is well defined. The next brood appears 

 in midsummer and is not as distinct as the spring brood. From this 

 time on there is a tendency to continual breeding until cold weather 

 appears, when, the adults entirely disappear, leaving only the fixed 

 forms firmly attached to the leaves, and no adults are to be seen until 

 the spring brood issues. 



At the time of the discovery of the pest in this city, the spring brood 

 was at its height, and thousands upon thousands of adult flies were in 

 evidence. From a knowledge of its life history, it was seen that the 

 first opportunity to attack the pest was immediately after the disap- 

 pearance of the adults of the spring brood, which would leave us only 



