1138 
Journal of Agricultural Research 
Vol. XXXI, No. 12 
♦ 
Say, and D. obliquus H.-S., according to determinations made by 
McAtee. None of these species, however, has appeared in cotton 
fields. 
DISTRIBUTION IN THE RIO GRANDE VALLEY 
The species is known to occur over an area extending from the 
Gulf westerly to Donna, Tex., or a little more than 60 miles, and 
from the Mexican border north to Lyford, Tex., a distance of about 
45 miles. The known area of distribution therefore contains several 
hundred square miles, and it is probable that this area will be con¬ 
siderably extended by careful scouting. 
In general, it can be seen that the insect occurs, perhaps contin¬ 
uously, from Central America, and probably farther south, along 
the Gulf Coast of Mexico to the lower Rio Grande Valley of Texas. 
MANNER OF SPREAD 
/ 
Little is known regarding the manner in which the insect occupies 
new territory. The present indications are that it has been present 
in the Rio Grande Valley for an indefinite period, although not 
Collected until recently. The adults are fairly strong fliers, and 
probably the area of infestation is extended mainly by flight. The 
young stages are gregarious and move in groups from plant to plant, 
but their progress is slow and extension in this way is relatively 
unimportant. 
FOOD PLANTS 
At Brownsville, Tex., the species has been found feeding in numbers 
upon at least four wild plants. These include (1) the plant which 
is apparently its natural host, Sida carpinifolia L., a member of the 
mallow family; (2) the common ragweed, Ambrosia artemisiaefolia; 
(3) wormwood, Ambrosia elatior L.; and (4) one of the sunflower 
family, Verbesina encelioides (Cav.) B. and H. Close observation 
of all these hosts has failed to reveal marked injury to flowers or 
seeds, and it appears that the feeding is mainly confined to sucking 
up the nectar produced by the plants. The writer has never been 
able, in the case of any plant, to find a definite injury to the living 
tissue which could be attributed to the attacks of the insects. 
In addition, adults have been observed in considerable numbers in 
many localities upon cotton plants. At Donna and Mercedes, Tex., 
inspectors of the Federal Horticultural Board report having observed 
considerable numbers of the immature stages in the cotton fields, but 
always in decayed bolls. As will be shown later, the very young 
stages subsist chiefly upon decaying vegetable material, or, perhaps 
more correctly, upon the juices which they can extract from this 
material. Adults have been observed in small numbers within the 
blossoms of many different plants, evidently in search of nectar. 
POSSIBLE ECONOMIC IMPORTANCE 
Whether the insect is economically important has not yet been 
definitely determined, although numbers have been observed and 
collected in cotton fields. The most valuable field observation yet 
made was contributed by T. C. Richardson, of Lyford, Tex., for 
