554 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
near-by mountain ranges of certain potential cotton pests which occur on a native 
plant, the so-called wild cotton, Thurberia thespesioides. These insects are a native 
variety of the boll weevil, Phytonomus grandis thurberiae Pierce, and a noctuid moth, 
Thurberiphaga diffusa Barnes, the larva of which is a bollworm. The native weevil 
is shown to have habits distinct from the Mexican boll weevil. Both it and the boll- 
worm are well adapted in their life histories to the normal late fruiting habit of the 
wild cotton. It is believed that either or both might, if proper opportunity were 
afforded become pests of domestic cotton. 
A problem is created by the fact that in the district cultivated about Tucson the 
wild cotton, harboring both insects, grows quite close to areas on which domestic 
cotton may be grown. Incipient infestations of the weevil, but thus far none of 
bollworm, have already occurred in the past few years but have been stamped out. 
At present there is a controversy to be settled by the courts between the Arizona 
Commission of Agriculture and Horticulture and the cotton growers of this district 
regarding the maintenance of a non-cotton area near the natural habitat of Thurberia. 
(Paper withdrawn for publication elsewhere.) 
THE CITROPHILUS MEALYBUG, PSEUDOCOCCUS GAHANI 
GREEN, AS A MAJOR PEST OF CITRUS IN SOUTHERN 
CALIFORNIA 
By H. M. Armitage, Entomologist , Los Angeles County 
Horticultural Commissioner's Office 
Abstract 
The citrophilus mealybug ( Pseudococcus gahani Green) first found in the citrus 
orchards of Southern California at Uplands, San Bernardino County in 1913, is now 
established in all of the southern citrus producing counties with the exception of San 
Diego and Imperial. In Los Angeles, Orange, San Bernardino and Riverside Coun¬ 
ties, it occurs over a rather large acreage. In Ventura and Santa Barbara Counties 
the infestations are new and as yet are confined to a limited acreage though none the 
less severe in degree of infestation. Due to adverse climatic conditions this species 
of mealybug has proven less serious in the interior counties as San Bernardino and 
Riverside and while the spread has continued the infestations have been exceedingly 
light since the date of the original outbreak. In the coast counties the spread has 
been rapid and the infestations as a whole very heavy. The citrophilus mealybug is 
particularly resistant to fumigation and has the usual resistance of this group of 
insects to sprays. Water under pressure during the peak of oviposition period in the 
spring is by far the most successful means of mechanical control. Natural enemies 
of which there are several native species present in the orchards are an important 
factor of control. The ladybird beetle, Cryptolaemus montrouzieri Muls.,an introduced 
predator, is particularly effective. Eight county and Association insectaries in 
Southern California are producing and libeiating monthly over half a million of these 
beetles, throughout the infested areas of Southern California. Where they are made 
available in quantity early in the year they are being used successfully as a control 
measure. 
The mealybugs^are not new pests to the citrus growers of California. 
The citrus mealybug (Pseudococcus citri Risso) has long been established 
