THE CONCHUELA. 49 
subdivisions of the estate to search for any particular insect concern- 
ing which information may be desired at headquarters. Tin'- sys- 
tem made it possible to obtain accurate information concerning the 
abundance of the Pentatomid bugs here considered. 
In 1903 the conchuelas were abundant only during the month of 
July and reached a maximum in numbers about July 20. Their 
first appearance was in the outlying districts, next to the mesquite, 
but they soon spread all over the cotton plantation, although they 
were more abundant in certain parts than in others. The insects 
disappeared early in August and did not reappear in noticeable 
abundance during the season, although the cotton plants remained 
green until October 17, when the first frost was recorded. 
Although a close watch for the insect was maintained during the 
late spring and early summer of 1904. the first specimen was not taken 
in the field until July 6. During the following seven days a rapid 
increase in its number- was noted, and on July 17 it was observed 
that a marked decrease had occurred. Nowhere on the plantation 
were the insects as abundant as in July of the previous year, nor 
were they so generally distributed. 
On August 31' a personal examination in the cotton fields by the 
author showed the insects to be very scarce, although in certain 
sections of the plantation the open cotton bolls with stained and 
ruined lint gave unmistakable evidence of their greater abundance 
a few weeks earlier in the season. 
In July, 1905, a detailed numerical study was made, which verifies 
Mr. Conduit's general observations for the two previous seasons. 
While the subject of natural enemies is discussed under a separate 
heading, it is necessary to mention here that the abundance of the 
conchuela during the season is principally dependent upon the 
efficiency of its parasitic and predaceous enemies. Egg-laying by 
the average individual i- distributed over such a long period of time 
that it can hardly be -aid that the conchuelas naturally appear in 
broods. However, practically the same effect may be produced 
locally to a greater or lex extent by the action of natural enemies. 
During the first two weeks of duly adults and nymphs in all stages 
were found in abundance on mesquite in the uncultivated lands 
Burrounding the Tlahualilo Cotton Plantation. The gradual ripen- 
ing and drying of the beans was evidently causing a migration of 
the adults in search of food, many finding their way into the cotton 
fields. Egg-parasitism was acting as a practically complete check 
on further multiplication in the mesquite. In their search for food 
the first migrants from the mesquite settled in large numbers in sec- 
tions of the plantation upon which zoca or seppa (stubble) cotton was 
growing, and later the migrants showed a preference for the planted 
22348— Bull. 86—10 1 
