8 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 1952 
FRUIT AND NUT INSECTS 
Citrus Blackflv Investigated 
"r»* 
Indian citrus black fly parasites show remarkable buildup in Mexico 
The relative importance of the four Indian parasite?, introduced 
into Mexico as pari of the Bureau"- cooperative work with Mexican 
authorities for control of the citrus blackfl}', has changed considerably 
over that of the previous year. Last year Prospalti lla sndtM was the 
only parasite that showed any promise. In the latter pari of 1951, 
.1 in Hits hesperidum and P. clypealis increased very rapidly and showed 
evidence of dominating P. smitM. A fourth parasite, ProspalteUa sp. 
near opuh ntty was set back considerably by having its two colony sites 
destroyed by the destruction of the trees on which they were estab- 
lished. In June 1951 a small number of adults was seen in a grove 
about 1 kilometer from one of the colony sites. Here the parasite lias 
been slowly increasing. P. smitM increased considerably in certain 
groves near Matlapa in the Valles region and in Cuernavaca. In one 
grove in Matlapa it increased steadily during the dry season from 
October to June. Good commercial control was obtained there 10 
months after the original release. More than 1,700.000 adults of this 
parasite were colonized in practically all of the blackfly-infested citrus 
areas of Mexico. 
Of all the Indian parasites now established in Mexico, Amitus 
hesperidum lias shown the most remarkable buildup and parasitiza- 
tion. It required about P/o years to adjust it-elf to i t r~ new environ- 
ment. During this time parasitization ranged from 1 to 10 percent. 
Beginning in June 1051 this parasite began to increase considerably 
in the Yalles and Morelos areas. By December parasitizations of 
from 80 to 90 percent were obtained in some groves. An estimated 
L24,000 adults of this species were liberated in the various citrus 
growing areas, mostly in the north. The development of P. clypealis 
in Mexico closely parallels thai of Amitus. Approximately 258,000 
adults of the former species were collected Between August and 
December 1951 and colonized in most of the citrus regions, especially 
in the area- of infestation nearest the United State-. Eretmocerus 
is, introduced into Mexico a few years ago. continued to exert 
a fairly high degree of parasitization in the more humid or wet areas 
along the West Coast, but appear- t<> be of little consequence in the 
i\v\ a ica-. 
Citrus black fly surreys 
Citrus blackfly surveys, begun in the fall of L949, were continued 
along the Mexican hoi-der during L951 in the States of Nuevo Leon. 
Tamaulipas, San Luis Potosi, and Baja California. Most of the sur- 
\c\ work has been done by Mexican nationals, working with Bureau 
pel- onnel. From light i<> heavy infestations were found in each State, 
with tin- exception of Baja California. The blackfly is established 
even there, but at points remote from t lie northern part of t he State. 
These surveys are for the purpose ^\' preventing the introduction of 
tin- insect into citrus groves in the United States. The pest is con- 
sidered «»iic of the mo t dangerous and difficult t<> control of all citrus 
insects. It was introduced into Mexico about L936. 
