102 MARYLAND AGRICULTL'RAL EXPERIMENT STATION. 



tuni) was aduudant upon the pears, attracted bv the Juice emerging from 

 the cracks, and almost every one of these ants carrieel on its l)ack one or 

 more specimens of the Coccid larvrt\ Sj)ecimens of a little Chrysomelid 

 h(iQ'(\.Q\Typophoi'u.s canellus) ss^^ii also found upon the trees. Red and 

 black specimens of these beetles occurred, and the interesting observation 

 was made that while the Aspidiotus larva^ crawled freely upon the l)lack 

 individuals, no specimens were to lie found upon the red ones. This 

 same peculiar fact was also found to hold with the ants, since the red ant 

 (^Forinica schat/fussi) was abundant upon the pears, but no s])ecimens 

 were found bearing As])idiotus larva-, while, as just stated, the little 

 black Monomorium was ahvays found carrying specimens. Curiously 

 enough, no ladybirds other than Pentilia were seen. The common Twice- 

 stabbed ladybird {Chilocorus bivulnerus), which is so active an enemy of 

 scale-insects and plant-lice throughout the Southern States, was absent." 



The scale-insects are, however, primarily carried to long distances, 

 Avhile shielded by the scales, through the instrumentality of man, upon 

 scions and nursery stock. The agency of wind has frefjuently l)een noted 

 in the more rapid spread of the insects in the direction of prevailing- 

 winds. '^I'his agency is not only direct, wherever tlie wind is sufficiently 

 strong, as in seA'ere storms passing over infested districts at the right 

 season, but it is also indirect in that the Hight of insects bearing the 

 young scale-insects is also influenced therel y. 'J'he voung scale-insect is 

 not easilv dislodged from the twig or l)ranch of a tree, but there is every 

 reason for believing that when the tree is very l)adly infested so that the 

 scales are literally piled one upon another, the young lice, finding no 

 means of sup])ort thereon, more readily attach themselves to the bodies 

 of other creatures or deliberately let tiiemselves droj), to be carried by 

 wind orbv running water, this last means being much more effective in 

 aiding their spread in countries which are dependent on artificial water- 

 supply and where irrigating ditches run near or through the orchards. 



As already indicated, it has l)een proved to have been introduced 

 from California on nursery stock at Parryville, N. J., and there are prol)- 

 ablv other centres of infection, like that in Missouri, from which the in- 

 sect has been brought diivctly from California. It would lie unjust, 

 however, to charge the nurserymen with the sole responsil)ility of this 

 distribution, because there is every reason to believe that it has been in- 

 troduced into other localities upon fruit, the rejected rind or peel of 

 which, carrying the insect, has been thrown out of car windows or from 



