23 
from there, however, or from Cuba. Steamers from both islands stop 
at Vera Cruz before reaching Tampico, and this would explain the oceur- 
rence of A. ficus in Vera Cruz. 
As to railway introductions, I[cerya purchast has probably been 
brought to Sonora from California in this way. It was most abundant 
at Magdalena, less so at Hermosillo, and still less at Guaymas. I was 
informed by Seiior U. Ferreira that it first appeared in Hermosillo during 
the yellow fever epidemic there eleven years ago, in 1882-83. It was 
first noticed in the plaza. The railway had recently been completed at 
that time. I do not see how else it could have reached Sonora from 
California than on orange cuttings. It is found in the interior of 
Tamaulipas (but not at Tampico), and in Nuevo Leon, and the most 
probable theory is that it spread to both regions in Mexico directly 
from California on cuttings. 
SCALE INSECTS MOST LIKELY TO BE INTRODUCED INTO THE SOUTHERN 
UNITED STATES FROM MEXICO, AND MOST TO BE FEARED, 
Aspidiotus scutiformis.—This is a very bad species, and is apt to reach 
the Southern States or California. Its northern limit, as at present 
known, is Monterey, where it is simply massed upon the leaves of the 
orange. It would most probably spread by rail, as it does not seem to 
be found at Tampico. it may be expected at any time in Matamoras 
and Brownsville (Texas). 
Pseudococcus yucce.—This is another very bad species, being particu- 
larly bad on orange at Guadalajara. It was originally described from 
California, but there is much danger of its reaching the Southern 
States from Mexico. It infests a great variety of plants, is a hardy 
species, and is wellspread over Mexico. Therefore it would be extremely 
apt to adapt itself readily to the Southern States, and should it reach 
there it would prove a most unwelcome pest. It would probably spread 
by rail, though there is also a probability of its being carried by boats 
from Tampieo. 
Orthezia insignis var.—This would prove, if anything, worse than 
either of the two preceding. It is very injurious on citrus fruits in the 
Guadalajara and Aguas Calientes region. It would probably spread by 
rail. Professor Cockerell informs me that this species has recently 
been sent him by Dugés from Guanajuato, which proves that it is 
beginning to spread. If the variety found in Vera Cruz by Cockerell 
is the same, it is already spread over a wide region in Mexico. 
Icerya palmert.—This species could not be found in Sonora by the 
writer. If it should spread, it would stand a very good chance of 
reaching California by rail. 
Aspidiotus articulatus.—This was found on orange in Tampico, asso- 
ciated with A. jficus. It could easily reach the Southern States by 
boats. 
Several other species, including Conchaspis angreci var. hibisci found 
