72 BULLETIN 647, U. S. DEPARTMENT OE AGRICULTURE. 
ness of natural enemies, especially certain internal parasites, partly 
to overcrowding of the trees by armored scales and white flies, and 
partly because of the poor physical condition of the trees. 
In Los Angeles County, Cal., where the trees are kept free from 
other scales and vigorously growing, the mealybugs increase tre- 
mendously as a result of ant attendance. Ordinarily they are kept 
under complete control, where the ants do not occur, by their preda- 
tory enemies. In orchards where fumigation has been neglected 
and the trees become overcrowded with the black scale, the mealy- 
bug does not benefit so much from ant attendance, and infestation is 
much milder. 
The fluted scale has never been found in the orange groves proper 
of Louisiana, and the part played by the Argentine ant in causing 
the outbreak of this scale at Xew Orleans in 1916 is not known. The 
occurrence of this outbreak, closely following the 1915 hurricane, 
suggests the probability that the insect was largely spread by this 
means. The fluted scale is unable, under present conditions, to thrive 
on the orange trees of southern California even under the heaviest 
ant attendance, apparently being held in check principally by the 
Australian lady-beetle (Novius cardinaZis Muls.), the green lace- 
wings, and the dipterous larva Cryptoc/iaetum monophlebi Skuse. 
While the black scale occurs in Xew Orleans under constant at- 
tendance by the Argentine ant, the ant has failed to bring it into 
prominence there, and not a single infestation or even a single speci- 
men has been discovered in any of the orange groves of Louisiana. 
In California the black scale infestations often become very severe 
after a single season during which fumigation has been neglected. 
In two years' time the insect is capable of increasing from almost 
none at all to such extreme numbers as to occupy every suitable 
feeding spot on the trees which it infests. Attendance by the ant 
for a single season does not noticeably increase the infestation of the 
black scale in California, where it reaches a maximum whether the 
ant is present or not. The natural enemies of this scale are not 
numerous and effective enough to control it. 
While exceptionally large numbers of the soft brown scale occur 
on certain host plants or parts of such plants under ant attendance in 
Louisiana, the natural enemies of this scale, especially the internal 
parasites, continue to hold it to insignificant numbers in the orange 
groves under present conditions. In Riverside County, Cal.. this 
scale appears to have increased considerably in certain ant-infested 
orchards, but is generally controlled along with other scales by fumi- 
gation. In Los Angeles County both the soft brown and the eitri- 
cola scales are scarce in ant-invaded as well as other orchards. The 
soft brown scale, however, is undoubtedly more numerous on cam- 
