February, '13] BISHOPP: stable fly 123 



Relation Between Grain Crop, Rains and Abundance of the 

 Fly. As has been pointed out, this insect is usually much more 

 numerous during the late summer and early fall months. When we 

 come to understand the breeding habits of this species this condition 

 is readily explained. A study of the recent outbreak in Texas clearly 

 shows that the unusual abundance in August and September was due 

 to the large crop of grain, incidentally producing a great number of 

 straw stacks, combined with the unusually heavy rains in early August 

 (at Dallas, Texas, 6.47 inches of rain fell). Many stacks were recently 

 thrashed and, being loosely piled, absorbed the rains as they fell. In 

 -a few days the entire mass became rotten and heated and thus afforded 

 precisely the conditions which are most desirable for the reproduction 

 of Stomoxys. It has also been found that during other years of unusual 

 abundance of this pest, the large grain crop and summer rains have 

 been the principal contributory factors. 



In Texas the activity of many adults has been observed rather early 

 in the spring. On May 18, 1912, the fly had become sufficiently 

 numerous at Dallas to greatly annoy cattle. During the latter part 

 of ]May it was found by Mr. Wood to be present in numbers at Abilene, 

 Texas. The flies which appear in the spring and early summer breed 

 largely, no doubt, in straw stacks of the previous year and in straw 

 used in feeding and bedding animals. 



Natural Control 



^ Climatic Influences. As has been mentioned, the presence or 

 absence of moisture in the breeding places of this species has a very 

 potent influence on development. The larvse are able to withstand a 

 great amount of moisture, often feeding on straw which is saturated 

 with water and thus being themselves largely submerged. It has been 

 found, however, that where there is a considerable depth of water above 

 the larvse they soon stop feeding and become dormant, not being able 

 to stand this condition more than a number of hours. The young 

 larvae are much more susceptible to injury by extremes of moisture and 

 temperature than are the well developed ones. In the case of the latter 

 pupation is often hurried as a result of these exposures. Larvse have 

 often been observed, when quiescent on account of lack of moisture, 

 to become active and resume feeding after water is supplied. The 

 pupse are much more resistant to the effects of both moisture and 

 temperature extremes. Light also has a very marked influence on 

 the development of larvse, particularly when they are small. In no 

 case have larvse been induced to complete development when kept in 

 tubes and exposed to bright light. As has been discussed under habits 



