THE CAMPHOR SCALE 3 



POSSIBLE MEANS OF DISSEMINATION 



It seems likely that most, if not all, of the infestations mentioned 

 above and shown in figure 1 have arisen from the setting out of in- 

 fested plants from other areas, as many of them have been traced 

 to shipments from Xew Orleans nurseries. It is improbable, how- 

 ever, that the scale is being distributed by movement of citrus fruits, 

 since there are few young beneath the parent scale at the time oranges 

 from the Gulf coast are picked and shipped. A limited dissemination 

 may take place through the movements of the insect itself, since the 

 newly hatched young may crawl for 24 hours or more after emerging 

 from beneath the scale covering, and thus become established on adja- 

 cent plants. Strong winds are also a factor in the local spread of the 

 insect, and undoubtedly there is some accidental transfer by birds, 

 insects, and other animals. The camphor scale does not secrete honey- 

 dew and consequently is not attended by ants, although the writers 

 have seen Argentine ants carrying the newly hatched young after the 

 scale covering had been removed. 



HOST PLANTS AND INJURY 



In Louisiana nearly 200 host plants have been found, many of which 

 are seriously injured by the scale. Because of its general use for 

 ornamental and shade purposes and the severity with which it is at- 

 tacked by the scale, the camphor-tree is probably the most important 

 host. Although trees are seldom killed by the scale, a continued in- 

 festation may kill back many of the twigs and devitalize the tree. 

 In such cases water sprouts usually arise near the base and, together 

 with the dead branches, give the tree an unsightly appearance (fig. 2) . 

 The females are found in the greatest numbers on the younger wood, 

 while the majority of the males go to the leaves. The tendency of 

 the crawlers to move towards the light and to the outer portions of 

 the tree, where the bark is more suitable for feeding, probably ac- 

 counts for the fact that the most injury is noted on the younger 

 branches and twigs. 



Satsuma orange is another favored host of the camphor scale. 

 The females attack all parts of this plant, settling readily on the 

 fruit. Since the infestation tends to reach its height about the time 

 the fruit matures, large numbers of mature scales are present on the 

 ripe fruit, and this reduces its market value. The scale may also 

 kill back some of the younger twigs unless it is brought under 

 control. 



On fig trees (Ficus carica var.) a large number of the females go 

 to the leaves, and since these are shed in the fall there is a natural 

 reduction of the population each year. When no control measures 

 are taken, however, the scale population on the branches may con- 

 tinue to increase. During 1930 and 1931 severe injury to figs was 

 observed on several trees that had never been sprayed. It seems 

 likely that one thorough spraying will protect the trees from injury 

 for several years. 



Other plants that are severely attacked include Japanese privet, 

 glossy privet, common camellia, sweet osmanthus, roses, confederate- 

 jasmine, and Kaki persimmon. 



