204 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



The damage is caused by the maggots in the ground when the beans 

 are planted. As the bean swells on sprouting, the larvae eat off the 

 plumule or tunnel in the fleshy cotyledons. The beans often develop 

 into stunted plants, known as snake heads, (PI. 9), which do not mature 

 and produce pods. If the cotyledons are above ground before the mag- 

 gots find the plant, the stem beneath the ground is attacked. After 

 eating its way to the pithy center the larva mines upward an inch or 

 more. 



There are two broods of flies each year in western New York and the 

 writer believes that in some years there is a small third brood. The 

 first flies emerged early in May in 1918 and there was a second brood 

 during the last half of June and the first part of July. The time from 

 egg to adult for bred specimens has varied between 25 and 47 days. 



Flies emerging in May are attracted for feeding and oviposition to 

 moist, freshly-plowed ground. The writer has found a few eggs on 

 newly turned soil and obtained others by throwing pails of water on the 

 ground around the laboratory. Several hours after the water was 

 thrown out eggs were found in these moist spots, though none could be 

 found in dry places. Eggs have also been found in large numbers 

 around decaying bean vines as well as rotting cabbage and clover 

 roots, and Prof. R. H. Pettit (in correspondence) reports breeding flies 

 from fresh manure and decayed clover stems. 



Many times in the literature reference has been made to decaying 

 material as a breeding place for the maggots of Phorbia fusciceps. 

 Schoene^ reports finding the larvae with those of Phorhia brassicce in 

 cabbage-heads and when so found, they were in the decaying part of 

 the plant. In examining bean fields, maggots have been found in 

 healthy plants, although they are found in much larger numbers in 

 beans which have begun to decay. As high as seventeen maggots 

 have been found in one rotting bean. 



If beans are planted when the ground is cold and wet, and the growth 

 is slow and decay sets in, maggots will be attracted from their feeding 

 places on buried clover roots or other decaying material to the beans 

 in large numbers. This influence of cold rainy weather on the growth 

 was demonstrated in the spring of 1917 when the rainfall at Rochester, 

 N. Y., in the bean-growing section of the state was 6.40 inches from 

 June 1 to July 1. Many growers lost their entire crop. In 1918 the 

 rainfall for this same period was 2.40 inches and on the whole a fine 

 stand of beans was obtained. 



The writer had hoped to find some material which applied to the 

 beans before planting would either repel the maggots or kill them as 

 they fed on the cotyledons. However, anything placed on the seed- 



1 Journ. Econ. Ent. Vol. 9., p. 132. 



