486 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



is that form of symbiosis occurring when there is a superabundance of 

 parasites of a single species attacking an individual host insect. Mul- 

 tiple parasitism is that form of symbiosis where the same individual 

 host insect is infested simultaneously with the young of two or more 

 different species of primary parasites. The term multiple parasitism 

 has already been used by Pierce to designate gregarious parasites and 

 while I dislike to use the same term for a different phenomenon I 

 know of no unused expression which fits so well this phase of parasi- 

 tism. 



In a brief paper like this it is possible only to touch upon the main 

 headings of the extensive subject of host-relationship of entomophagous 

 insects. It has been attempted to define only the most important 

 divisions, but each of those is of course divisible into a number of 

 lesser types. While the writer is not so rash as to believe that there 

 will be a general acceptance of these definitions by entomologists, he 

 does hope that they will be of some assistance to students of this most 

 interesting phase of biology. 



Chairman H. J. Quayle: The next paper will be on the dispersion 

 of scale insects by the wind. 



DISPERSION OF SCALE INSECTS BY THE WIND' 



By H. J. Quayle, University of California, Citrus Experiment Station. Ririr.side, 



CaUfornia 



The manner and extent of dispersal of many insects have been 

 largely conjectural until recent years, and even now exact data have 

 been secured for comparatively few species. Of course, we have had 

 records of the great distances that certain flying insects may travel. 

 It is only necessary in this connection to mention such insects as the 

 migratory locust, Schistocerca peregrina, which has been found five 

 hundred miles east of its home in South America and is supposed to 

 have crossed over even to Africa, or our own Rocky Mountain locust, 

 which has gone one thousand miles from its breeding ground, or certain 

 moths that have been seen over four hundred miles at sea. 



It is only recently, Icwevcr, tbct we have come into possession of 

 definite data as to how far such f.yiig injects as tl.e house-fly or such 

 non-flying forms as gipsy moth larvse may travel. Without authentic 

 data, a few hundred feet or a few hundred yards was thought to be the 

 limit of travel of the hoi se-fiy. The work of Arnold, Copeman,et al, 



1 Paper No. 36, Citrus Experiment Station, College of Agriculture, University of 

 California, Riverside, California. 



