14 BULLETIN 134, U. S. DEPARTMENT OF AGRICULTURE. 



In Sicily the black scale was seen in great abundance in several 

 places, but these places usually consisted of but a small area, or even 

 but a few trees. (PL II, fig. 1.) It is found in scattering numbers 

 throughout the citrus area, but with the exception of a few cases of 

 dirty fruit which have been seen, coming from limited areas, as noted 

 above, the black scale is not a serious pest in this, the most important 

 lemon section of the Mediterranean. It is the writer's opinion that, 

 above ail other factors, the absence of the scale in serious numbers in 

 Sicily is due to the sirocco, which frequently prevails there during the 

 summer and fall. This is a burning hot, dry wind from the African 

 deserts. It is only necessary to experience one of these siroccos, 

 which usually lasts about three days, to conclude what effect it would 

 have on insects not well adapted to withstand heat and dryness. 

 Opportunity was afforded for judging the effects of a sirocco on 

 young black scale in Sicily, with the result that between 95 and 100 

 per cent were seen to be killed. The same effect of hot weather has 

 been observed by Mr. C. L. Marlatt, 1 Mi-. R. S. Woglum, 2 and the 

 writer 3 in California. 



SEASONAL HISTORY. 



So far as could be observed the black scale has very much the same 

 life and seasonal history in Mediterranean countries as it has in Cali- 

 fornia. The majority of the young appear in June and July. These 

 settle almost entirely upon the leaves or on the tender twigs. It is 

 during this period that high temperatures are likely to cause a heavy 

 mortality. Later in the fall the young that still survive migrate to 

 their permanent abode on the twigs and branches, and pass the 

 winter as partly grown insects. During this season growth is very 

 slow, but with the resumption of warm weather in the spring it pro- 

 ceeds rapidly. By May and June oviposition occurs, and from 2,000 

 to 3,000 eggs are deposited by a single female during a period of 

 from 30 to 60 days. While the majority thus mature in the spring 

 and require 8 or 10 months for development, others, that have all the 

 heat of summer, will mature in 4 or 5 months, and thus some scales 

 will be found in all stages at all seasons. 



NATURAL ENEMIES. 



The most important natural enemy of the black scale in most- 

 sections where it occurs is Scutellista cyanea Motch. It was a sur- 

 prise, however, to find that this parasite occurred in less numbers in 



i Marlatt, C. L. Insect control in California. U. S. Dept. Agr. Yearbook for 1896, p. 217-236, PI. V, 

 1897. See p. 218. 



2 Woglum, R. S. Fumigation investigations in California. U. S. Dept. Agr., Bur. Ent., Bui. 79, 73 p., 

 28 figs., June 11, 1909. See p. 12. 



3 Quayle, H. J. The black scale. Cal. Univ. Coll. Agr. Expt. Sta. Bui. 223, p. 151-200, 24 figs., 8 pi., 

 July, 1911. Seep. 165. 



