234 Journal of Agricultural Research voi. xvi, no. 9 



Formation of the; puparia. — The mature larvae escape through the 

 epidermis of the leaf, but seldom make their exit through a definite hole. 

 Usually the upper epidermis become dry and parchment -like, rupturing 

 itself and allowing the larvae to escape. Sometimes the larvae cut circular 

 holes through the epidermis. They fall to the ground and ordinarily 

 penetrate the soil to a depth of 2 or 3 inches. If the ground is hard, they 

 do not enter, but form their puparia beneath leaves or other rubbish. 

 The depth to which the larvae penetrate varies considerably. To determine 

 this, a few experiments were performed with full-grown larvae. For this 

 purpose a root cage was used, having a space of X inch between the glass 

 and the back. This space was filled with loose sandy soil. The surface 

 of the earth was covered to prevent the larvae from eacaping. This dark- 

 ened the top of the soil and slightly altered normal conditions. 



Twenty-seven mature larvae were placed on the surface of the soil. 

 The following day eight puparia were found on top of the earth. The 

 remainder of the larvae either failed to transform or escaped. In a second 

 experiment 32 mature larvae were placed on the surface of the soil. Four 

 larvae transformed on the surface, six were found at a depth of 2 inches, 

 one at a depth of 5 inches, and two at a depth of 6 inches. These experi- 

 ments, though few in number, give some idea of the depth to which the 

 larvae penetrate loosely compacted soil. 



In captivity many of the larvae formed their puparia within the leaves. 

 Mined leaves were collected in large numbers and put in receptacles to 

 obtain puparia. In most cases the puparia were found in the leaves or 

 between the leaves from which they had issued. A few of the larvae 

 wandered about in an attempt to find a more suitable place in which to 

 transform. Evidently many of the lar\^ae under natural conditions never 

 enter the soil. 



Adults. — While working with the adults, the writer had an oppor- 

 tunity to experiment with several types of rearing cages. A cage similar 

 to the Riley cage, covered with cheesecloth on three sides and with glass 

 on the fourth, gave good results when large numbers of individuals were 

 used, but proved useless for individual pairs of flies. Glass cylinder 

 cages (PI. 29, B) }delded better results for this purpose, but were unsat- 

 isfactory because the adults escaped when the cylinders were lifted. 

 The most satisfactory type of cage proved to betheFiskecage (Pi. 29, A,C), 

 used a great deal in the rearing of parasites by the United States De- 

 partment of Agriculture at Melrose Highlands, Massachusetts. The 

 small opening at the top readily permits one to introduce food, while the 

 ring at the bottom prevents the flies from escaping. 



In spite of all the precautions in handling and feeding the adults, they 

 did not live long in captivity. One male was kept alive for 18 days. 

 Table III gives the length of life of the males and females as obtained 

 from pairs that were kept in captivity. 



