December, '17] KELLY: BIOLOGY OF C(ELINIDEA 531 



Packard, Larrimer, and the writer, it was found that the larva feeds 

 greedily during the week or two following the pupation of the Meromyza 

 until it consumes the juices of the Meromyza larva within the pupal 

 case, where it also pupates later. The pupal stage of Co^linidea is 

 very short in the laboratory, being not more than eight or ten days. 

 However, in the field, observations indicate that the pupal stage may 

 be longer. 



Observations in the field during the spring of 1915 indicated that 

 the adult parasites were abroad at the same time as the Meromyza 

 adults, and they readily oviposited into the eggs of the Meromyza in 

 the field. Collections of Meromyza larvae made in May and June 

 gave up the parasites in about twelve to fifteen weeks after oviposition 

 was observed, some of the parasites, however, remaining in the plants 

 until fall. During early September, Meromyza adults were quite 

 plentiful, depositing a large number of eggs on the wheat plants. But 

 it was not until the latter part of September that Ccdinidea meromyzce 

 were observed, and then in large numbers depositing eggs into the 

 Meromj^za eggs which were just about readj^ to hatch. Some of the 

 infested wheat plants collected in November wete placed in a warm 

 room at the laboratory and from these issued adult Meromyza and a 

 number of adult parasites in January, 1916. A lot of plants collected 

 at the same place were left in outdoor cages, but from these the host and 

 parasites did not issue until the middle of April. 



The indications are that there are two annual broods of the parasite. 

 However, this may vary, because there are some indications that there 

 are more than two broods of the host. It appears probable that if 

 weather conditions are right, and the Meromyza puts out an extra 

 brood, there will be an extra brood of the parasite. From a number of 

 infested plants collected in 1914 and 1915, the percentage of parasitism 

 was apparently not sufficient to be a controlling influence on the host. 

 However, Dr. Forbes and Professor Osborn state that this parasite is 

 evidently a controlling parasite of the wheat bulb-worm in lUinois 

 and Iowa. This may be universally true, because in localities observed 

 there has not yet been a really serious outbreak of Meromyza ameri- 

 cana, though it frequently does more or less damage to wheat. 



