12 MONTANA EXPERIMENT STATION BULLETIN 238 



the seed pod in the growing croii and emerge by gnawing small, 

 circular holes through seed and pod about the time the crop is har- 

 vested. A second generation matures in the seed in the spring. 



This insect has been in jiarts of ^Montana for some years and 

 vmne to prominence in 1930. when seed-houses found rather severe 

 infestations in seed from ]\rontana growers. This insect is of im- 

 portance not only liecause of the actual loss to the seed crop, but 

 because of a natural fear of spreading it through sale of infested 

 seeds. 



There is need for further work on this chalcis fly in Montana to 

 determine in just what parts of the State it is present and whether 

 the method of early cutting of the crop for hay. in advance of the 

 date when the adult "flies" are ready to lay eggs, as practiced in 

 rana(h). would be effective under our conditions. 



THE WOOLLY APHIS OF THE APPLE 



Sfliizoneiira Innigera Hausin. 



The woolly aphis has been a persistent enemy in some parts of 

 I\Iontana for years, particularly in the commercial orchards in the 

 Bitter Eoot Valley. During the season of 1930. an effort was made 

 to determine whether or not the well-known parasite, Aphelinus mali, 

 was present in the Bitter Eoot Valley. 



In i^>?.^introduction of parasites for the control of an insect pest, 

 it is necessary to determine first whether or not the parasite it is 

 l)roposed to bring in is already present. The woolly aphis is usually 

 spread to new localities on the roots of nursery stock and on the 

 roots there is little chance of parasites being present. This is one 

 of the pests on which parasites have been used artificially with much 

 success. It is proposed to bring in and liberate parasites in the 

 Bitter Eoot Valley, in case they are not already there. This season's 

 work did not reveal any of the parasites in the orchards of the 

 Bitter Eoot Valley. 



THE DLA.MOND-BACK MOTH 



Plutolla maculipennis Cuitis 

 One of the unexpected developments of the year 1930 was the 

 appearance of great numl)ers of this very small caterpillar on mustard 

 crops grown for seed. ^lore commonly this insect is a pest on small 

 areas of field and garden cabbages and related plants. The trouble 

 was brought to our attention too late for assistance to be given this 

 vear. but farmers were advised that the insect can be controlled hv 



