W. M. DAVIDSON 43 



adept at concealing tlie(ns(^lves from the lit»;lit. TIkmt 1)(>liavi()ur 

 in this respect was very (Hssimikir to that of tiic larvae of other 

 aphidophao'ous species, such as Catahomha ]>yraMri Linna(>us, 

 Syrphuf; nitcns Zettcrstedt, and Eupeodes volucrtH Osten Sacken, 

 under sinmltaneous ol)servations. This fact suggests that nor- 

 mally McUinostouia larvae feed at night. 



The ])ui)ai-ium of M. xlegnuw is light brown in general apjx'ar- 

 ance. The integument becomes slightly more opaque with 

 age, but is never more than semi-transpai'ent. Tlie an((M-ior 

 end is nioderately bulbous. In outline the dorsum descends 

 posttM'iorly in an even ai'ch and the center is hardly coucma'c. 

 Length, li mm., maximum height and width, 2 nun. 



Allowing file female flies a pre-oviposition pei'iod of five days 

 Ihe life cycle of M. stcg/nnn was completed in two months. 



Melanostoma chaetopoda new species 



Two gi'avid females were collected in a field of peas infested 

 with MacroKiphum pisi Kalt., on Novembei- 5, 1919, transported 

 to the laboratorj^ at Alhambra and placed in small wire screen 

 cages enclosing pea plants infested with this ajihid. The flies 

 were fed diluted honey. Both died on November 7, each having 

 deposited one egg. These eggs hatched in eight daj^s, and the 

 i-esul1ant larvae were placed in glass vials and offered a])hids. 

 One pupated on December 2 after a larval instar of twenty-six 

 days, and the other was full grown on Novemljer 29 and remain- 

 ed alive without pupating until January 9, 1920. Both lai'vae 

 were fed Alacrosiphiim pisi, and after November- 23, when they 

 cast the second molt, food records were ke])t. These showed 

 that each of the larvae consumed nineteen a])hi(ls in the fourth 

 instai'. On January 2, 1920, a male fly e:aierged. 



]^etwe(-n February 16 and April 4, 1920, seven females were 

 collected in th(^ field, transported to th(^ insectaiy and i)lacetl in 

 cag(^s enclosing plants infested with a])hids. Three deposited 

 res])ectively four, six and three ova, the other four failing to 

 oviposit and were possibly sterile. These females were fed with 

 sugar water and livcnl in the cages from two to thirty days. Ten 

 out of thirteen ova hatched after an average inculcation stage of 

 five and one-half days. On March (i three larvae issued; from 

 March (3 to 12 these were fed MacrosipliKni pisi, fi-om March 



TKAN'S. A.M. ENT. SOC, XI.XIII. 



