224 



ventral median ridge. The skin then splits, not on the dorsum, as 

 would be exi^ected. but either at the anterior end or underneath the 

 head. The head and prothorax are then imshed out and the skin is 

 gradually worked backwards by means of the abdominal motions, the 

 portion already out swelling as soon as it is free. 



By the end of June the adults begin to issue in numbers, and exr>eri- 

 ments were made at this time to ascertain the length of life of the adult 

 with the result that while one individual lived for 20 days, the great 

 majority died before the end of 9 days. Some experiments made dur- 

 ing the latter half of May show that the life duration is considerably 

 shorter in the spring, the longest lived individuals reaching only the 

 age of 7 days. Eetarded individuals in the Insectary emerged the 

 middle of August. 



Eggs were again laid by these adults ar.d since no furtlier flight of 

 adults was noticed, full-grown larva- from these eggs in the main car- 

 ried the species through the winter, making but two annual generations. 



The dates given in the above account of the life history correspond 

 reasonably well with those of corresponding i^eriods in the insect's life 

 in Florida, as indicated by the receipt of many si^ecimens from Mr. C. 

 H. Foster, of Manatee, during April and May. March 31 the specimens 

 received from this gentleman were all in the last laval or pupal stage. 

 April 6, eggs had already been laid, and from his correspondence we 

 gather that oviposition continued until April 19. In a letter just 

 received Mr. Foster informs us that adults were observed flying during 

 March and April, June and July, and in September, thus indicating 

 three annual generations in Florida. 



In Louisiana, where the insect is known as the '• White Fly," the 

 species hibernates in the same way, as we learn from Prof. H. A. ]\ror- 

 gan, and is especially injurious to nursery stock, causing a very marked 

 check in the growth. 



EE3IEDIES. 



The most satisfactory remedy consists in the use of the ordinary kero- 

 sene emulsion sprayed at the proper time. Mr. Foster was kind enough 

 to send us the most abundant material from trees in his orcnard which 

 lie sprayed with standard emulsion upon our recommendation in the 

 spring of 1892, and from careful laboratory examination of this material, 

 from both sprayed and unsprayed trees, we are able to speak with some 

 certainty as to the eifects of the apphcations. In February Mr. Foster 

 wrote us concerning an application which he had made of a lime and 

 sulphur wash to a certain proportion of his trees. Samples which he 

 sent indicated that more than half of the insects upon the treated trees 

 were still alive. We advised him to substitute the kerosene emidsiou 

 and to spray at the time when adult insects were most abundant and 

 again at the time when the young lice had issued for the most part. 

 His first kerosene emulsion spraying was performed on March 30, and 

 examination ^owed that out of a total of 229 full-grown larva? and pupie 

 157 had been killed by the application. Later spraying was performed 



