10 CIRCULAR 3-49, U. S. DEPARTMENT OF AGRICULTURE 



16% inches being the maxim um depth at which one was found. The 

 surface of the soil of those pits that had not been dug at the time this 

 observation was made was carefully examined. Xo emergence holes 

 were noted except at the edges of the pits where fissures in the soil had 

 opened. It is improbable that there were any beetle pupae below 

 the bottoms of the pits. 



After the period when there was any possibility of adults of Anas- 

 trepha ludens emerging from the soil of the pits, it was observed that 

 irregular cracks or fissures opened around the edges of the pits when 

 a few hot, dry days followed a rainfall sufficient to moisten the soil to 

 a depth of several inches. Upon measuring the fissures of two pits 

 of each series, they were found to have maximum depths ranging 

 from 2 3 i to 4}i6 inches and maximum widths ranging from three- 

 sixteenths to seven-sixteenths inch. 



Since fissures may open at the edges of the pits and burrowing 

 insects may open passageways that might enable Anastrepha ludens 

 adults to escape from the soil, it is recommended that burial pits be 

 examined occasionally to make sure that there is no possibility of 

 adult emergence through such fissures or passageways. 



EXPERIMENT IN 1932 



The results of the 1931 experiment showed that the packing of the 

 soil in which infested fruit was buried was of considerable importance. 

 For that reason all the sand used in the newly dug pits the following 

 year was packed in order to procure more data on this factor'. 



In this experiment 4 pits filled with packed dry sand and 4 pits filled 

 with packed moist sand were used. The sand was thoroughly dried 

 by spreading it on a tarpaulin. It was uniiomily moistened, care 

 being taken not to add too much water. When moistened, the sand 

 was not flocculated. The pits of the two series were arranged alter- 

 nately. They were covered with the cages used in the previous 

 experiment. 



The eight pits were all dug some time previous to the start of the 

 experiment, close to those made the previous year. They were of the 

 same size, 2 by 2 feet, and about 20 inches deep. The measurements 

 were made from the bottom upward because some of the pits were 

 made slightly deeper when the bottoms were leveled. To accomplish 

 this with accuracy a 1- by 2-inch stake was placed about 2 inches out 

 from one wall of each pit. The stake was marked at 2 inches and at 

 20 inches. Thus when sand was placed in the pit, the top was 20 

 inches from the bottom or 18 inches from the top of the mangoes. 

 The tamper used the previous year was used again, but it was too 

 large to pack the sand in the immediate vicinity of the stake. This 

 source of error was eliminated by tightly packing the sand every few 

 inches around the stakes with a small piece of wood when the pits 

 were being filled. 



The fine river sand used in this experiment was first sifted to remove 

 any foreign material that might have been present. The sifting of a 

 sample weighing 345.4 grams showed that 77.8 percent varied from 

 x to 0.5 mm, 15.7 percent from 0.5 to 1.0 mm, and 6.4 percent from 

 1.0 to 2.0 nun in size. 



One hundred mangoes that appeared to be well infested were placed 

 in a single layer at the bottom of each pit. These layers lacked but 

 little of being 2 inches in depth. Care was taken to make sure that 



