664 Journal of Agricultural Research voI.xxi.no.q 
the young larvae, either from moisture (mildew) or cold, appeared to be 
higher than at other times. The greatest development of the scale is 
possibly reached in the spring (April to June). This is the so-called 
spring migratory period when the young leave the old areas of infestation 
and migrate up on the bole and out on the new growth of offshoots to 
new areas. From the old center of infestation in the area of last year’s 
fruit stems the new center of infestation is moved to the area of the fruit 
stems of the current year. This is accomplished by actual migration of 
the young larvae to the new leaf and fiber tissues above and to the leaf 
pinnae. That by June many of these larvae are killed in the exposed places 
is evident. From about the middle of April palms with heavy infestations 
show quantities of cottony masses out on the fronds and new fruit stems 
and on the new growth of their offshoots. By July this has practically 
all disappeared. 
Mr. Shamblin has often observed a fall migration similar to the spring 
migration. It is much less severe and the “cotton” of the exposed in¬ 
sects is usually found out on the fronds of the offshoots and parent tree 
during September and October and disappears almost entirely by the 
latter part of November. The occurrence of this migration depends en¬ 
tirely upon weather conditions, a cool fall usually bringing on a migra¬ 
tion. No fall migration was noted in any gardens during 1919. That 
this appearance of the insect is usually of relatively small proportion 
(less than half of the spring generation) and often is completely con¬ 
trolled by weather conditions makes it of much less importance than the 
spring occurrence. 
In Tempe, Ariz., there is much less scale development than in the 
Coachella Valley, possibly due to a moister climate. This in a way 
corroborates the observations on the mortality of the young scales during 
January, 1920. Mildew seems to form quickly in the scale mass when it 
becomes too moist. The preferred feeding place of the scale (the soft 
living tissues of the leaf bases and fiber strands) is found to be cool and 
slightly moist even on the hottest day. This possibly explains the mor¬ 
tality among the exposed scales under the hot, dry condition of summer. 
CONDITION OF FRUIT STEMS AT DIFFERENT SEASONS 
A study of the progress of the infestation on the leaf bases and fruit 
stems cut from heavily infested palms at different seasons of the year 
proved most interesting. It shows clearly how fruit stems of the cur¬ 
rent year become infested from the spring migration and also shows the 
development of the scale. 
There are usually from 5 to 7 leaf bases between the tip of the crown 
and the fruit stems of the current year and live leaf bases between the 
fruit stems of each succeeding year. The leaf bases are arranged in a 
