LOUISIANA CIRCULAR No. 4. IT 



The spread from orchard to orchard, or from one tree to 

 another in any given orchard, is entirely through the agency of 

 the young crawling lice. As the males, although winged, can- 

 not of themselves disseminate the species and as the females re- 

 main in one spot during their entire lifetime, it will be seen that 

 neither the adult females nor males can directly cause new in- 

 festations, or even infestation of adjoining trees. However, the- 

 young lice crawl about readily* during the first few hours of their- 

 existence and where the branches of the trees interlock they crawl 

 readily from one tree to another. Birds, alighting upon badly- 

 infested trees, get the small lice upon their feet and when they 

 afterwards alight upon other trees the lice crawl off to locate 

 upon the twigs and limbs and commence their development. The- 

 transportation of the lice by birds is of such common occurrence 

 that many inspectors, when entering an orchard for the purpose 

 of looking for San Jose scale, go directly to birds' nests, if any 

 are in view, and examine the twigs immediately surrounding 

 them. In nearly all infested orchards, and even in many cases 

 where the infestation is still very light, the scales are found in 

 greater abundance around birds' nests than elsewhere in the im- 

 mediate vicinity. This also accounts for the fact that a belt of 

 heavy timber between orchards is a very effectual barrier to the 

 natural spread of the scale from one orchard to the other. Birds 

 coming from an infested orchard are not likely to pass through 

 a belt of timber to another orchard without alighting upon the 

 forest trees and loitering about more or less, during which time 

 the lice upon their feet and legs have an opportunity to get off. 

 It is quite likely that the many large insects which frequent or- 

 chards are instrumental in carrying the young San Jose scale 

 lice from tree to tree, and in fact the writer once found two of 

 these young lice upon a large flower beetle (Allorhinn} taken in 

 an orchard where the scale occurred. 



Horses and mules used in cultivating orchards and nurseries? 

 jar the limbs with which they come in contact and thus get the 

 young lice upon them. The lice are again rubbed or shaken off 

 on to other trees some distance away, as is evidenced by the fact 

 that in peach orchards where the cultivation is in only one direc- 

 tion the spread of the scale is invariably greatest in the direction 

 of cultivation and not at an angle to it. 



