8 BULLETIN- 812, U. S. DEPAETMEiNTT OE AGKICULTUEE. 



and is almost free from pubescence. The 13 body segments are at 

 times quite prominent. 



PUPA. 



The pupa (PL I, C) measures 1.8 mm. long. It is at first white, 

 later the eyes and ocelli are brown, and before becoming adult the 

 pupa turns black. All appendages are folded close to the body, and a 

 thin pupal skin covers the insect in this stage of its development. 



ADULT. 



The adult (PL I, A) of B. funehris is a very small black insect 

 measuring about 2 mm. in length. Frequently thousands are seen 

 flying over the horses and mower when the alfalfa seed crop is being 

 harvested. They also collect in great swarms on the shady sides of 

 alfalfa seed stacks, from which these insects emerge. Farmers fre- 

 quently mistake the adults of this species for gnats, which are about 

 the same size and are frequently very troublesome at the time when 

 the chalcis-fly is most abundant. 



SEASONAL HISTORY. 



EARLY DEVELOPMENT. 



The first development of the chalcis-fly may be found in February 

 and March throughout the Southwest, when the hibernating larvse 

 begin to transform to the pupal stage. Spring temperatures and 

 moisture conditions determine the time of this transformation. In 

 colder climates it is much later, and under desert conditions the 

 larval stage may be prolonged indefinitely. 



FIRST APPEARANCE OF ADULTS. 



The first adults appear in the spring, about four or five weeks after 

 warm weather has set in. It is probable that in southern California 

 adults may be active in small numbers throughout the entire winter. 

 Adults of B. funebris were taken in the fields in the San Fernando 

 Valley, Calif., as early as March 3, but they usually do not appear 

 in large numbers until about April. At Yuma, Ariz., they make 

 their appearance in March, and the first seed pods, which usually 

 develop along the check ridges, become infested by the middle of 

 April. On April 17 green pods were taken at the edge of a field at 

 Yuma, and upon careful examination, 8 seeds showed very small 

 larvae, 5 showed half-grown larvae, 15 showed full-grown larvae, and 

 20 showed B. funehris pupae. E. G. Kelly observed adults of B. fune- 

 hris in the field at Wellington, Kans., as early as April 21. H. T. 

 Osbom reared them in out-of-door breeding cages in the same 

 locality as early as April 17. In the valleys of central California 

 the adults of B. funehris become active in April and oviposit into the 

 seed pods of bur clover {Medicago hispida), which forms seed pods 

 much earlier than alfalfa. 



