594 DIPTEKA. 



or milk ; and this statement agrees with the observations of 

 Mrs. Gage. 



The flies are not confined to wheat alone, but deposit in 

 barley, rye, and oats, when these plants are in flower at the 

 time of their appearance. I have found the maggots within 

 the seed-scales of grass, growing near to wheat-fields. The 

 eggs hatch in about eight days after they are laid, when the 

 little yellow maggots or grain-worms may be found within 

 the chaffy scales of the grain. Being hatched at various 

 times during a period of four or five weeks, they do not all 

 arrive at maturity together. Mrs. Gage informs me that 

 they appear to come to their growth in twelve or fourteen 

 days. They do not exceed one eighth of an inch in length, 

 and many, even when fully grown, are much smaller. From 

 two to fifteen or twenty have been found within the husk of 

 a single grain, and sometimes in every husk in the ear. In 

 warm and sheltered situations, and in parts of fields protect- 

 ed from the wind by fences, buildings, trees, or bushes, the 

 insects are said to be much, more numerous than in fields 

 upon high ground or other exposed places, where the grain 

 is kept in constant motion by the wind. Grain is commonly 

 more infested by them during the second than the first year, 

 when grown on the same ground two years in succession ; 

 and it suffers more in the immediate vicinity of old fields, 

 than in places more remote. These insects prey on the 

 wheat in the milky state, and their ravages cease when the 

 grain becomes hard. They do not burrow within the ker- 

 nels, but live on the pollen and on the soft matter of the 

 grain, which they probably extract from the base of the 

 germs. 



It appears, from various statements, that very early and 

 very late wheat escape with comparatively little injury ; the 

 amount of which, in other cases, depends upon the condition 

 of the grain at the time when the maggots are hatched. 

 When the maggots begin their depredations soon after the 

 blossoming of the grain, they do the greatest injury ; for the 



