THE MONTHLY BULLETIN. 477 



salutary effect upou the work in many cases, although in only one case has it been 

 found necessary to resort to drastic measures with a fumigator. All tents must be 

 plainly marked to indicate distance over, and taped to determine circumference and 

 dosage required. All work, both fumigated and sprayed, is critically examined by a 

 competent entomologist who devotes his entire time to this work for five months each 

 year, and renders an exhaustive report to this office which gives us a very close check 

 on the efficiency of each job as well as the work of each fumigator for the season. 



The details of procedure in this work are as follows: The night inspector furnishes 

 the investigator a report on each orchard, covering name of owner, fumigator, date 

 of fumigation, acreage, variety, schedule used, time of exposure, number of tents, 

 direction pulled, average temperature, and humidity. The first investigation is made 

 not less than one month after treatment and a similar one not less than one month 

 later, the result being based on an average of these investigations which is made in 

 the following manner: The investigator takes sample leaves from each tree at the 

 head of the orchard or the first tree shot in each row. These are placed iu a 

 sack. lie then proceeds diagonally across the orchard to the opposite lower corner, 

 taking samples from each tree passed. These are placed in a separate sack. Samples 

 from each tree at the foot of the orchard or last one shot in each row are placed in 

 still another sack. He then goes diagonally across to the point of starting and these 

 samples are placed with those of the other diagonal row, and represent the main 

 body of the orchard. The report on each orchard is thus rendered in three parts, 

 namely : on the first tree shot iu each row, on the main body, and on the last tree 

 shot in each row. The result of each investigation is an average of these three 

 reports which are secured by an actual count, under a glass, of all scale alive and 

 dead. From this is figured the per cent efficiency of the work, although this of 

 course does not determine the percentage killed by the treatment, as we have no way 

 of knowing by what means the insect died. All samples are taken from the lower 

 part of the tree. While this plan can not be followed in detail in all eases as where 

 the tents are pulled in various directions or iu irregular shaped orchards, we believe 

 it is as near perfect as any practical method of investigation that can be devised. 



The report for the season of 1916 shows au efficiency for each of the six fumigators 

 ranging from 97 to 9S.12 or an average of 97.65 for all work done. The spray work 

 of which there was about 1,500 acres mostly with oil-sulfur, pyrox, and shure-kil 

 sprays ranged from 50.3 to S7.S6 efficiency so far as kill was concerned, but this does 

 not take into consideration the very frequent and often serious damage done to tree 

 or fruit of which there was practically none in the fumigation work. 



We find that very often in spray work the bad results are not evident until the 

 following year, when, as in the case of pyrox, there is frequently a more or less 

 severe dying back of the smaller twigs. More disastrous results, however, have 

 followed the use of this spray here through the destruction of the ladybird enemy of 

 the cottony cushion scale, viz, Vedalia cardinalis. Death of this valuable predator 

 is probably due to the arsenic contained in this spray. The cottony cushion scale 

 has increased to an alarming degree, at times totally destroying the crop and even 

 threatening the life of the trees in some orchards. Shure-kil proved such a "frost" 

 that it was banished from the county after the second year. 



A great many different kinds of sprays have been tried here for the control of 

 gray scale, and in no case has the result justified the substitution of spray for 

 fumigation in this work, the expense of the spray invariably being the greater wheu 

 efficiency is considered. Very few growers spray the second season, but too many 

 insist on being "stung" once. 



From observation of results so far obtained in this county, this office can not 

 recommend any spray for citricola scale except on very young trees or in isolated 

 cases where for certain reasons fumigation is not practical. 



