184 



VEGETABLE INSECTS 



Professor Herrick: The dirt is packed up carefully 

 along the edges so the flies cannot get under and they can- 

 not get down in. 



Question: How long after the plants are transplanted 

 will it be before the flies lay their eggs? 



Professor Herrick: That will depend on whether you 

 are planting the late cabbage or the early cabbage. On Long 

 Island the flies appear by the middle of April sometimes, and 

 from that up to the first of May. 



Question : How long do you leave those tarred papers 

 on? 



• Professor Herrick : They can be left on till the cabbages 

 get a good strong start and will probably do no harm if left 

 indefinitely. 



Question: Do those papers interfere with working your 

 crop? 



Professor Herrick: They will interfere to this extent, 

 that they ought not to be covered with dirt when you are 

 cultivating. You can not cultivate quite so close because if 

 you cover them with dirt, the fly will deposit its eggs there. 



Cabbage Aphis. 



The cabbage aphis is one of the injurious insect pests upon 

 cabbages in the central part of New York State at least. 

 In some seasons it appears in great numbers, in other sea- 

 sons it is not abundant. For the past few years it has been 

 abundant and has caused a great deal of injury in this state. 

 Two or three years ago we studied the life history of the 

 aphis very carefully and carried out some experiments in 

 controlling it. If we study the life history and habits of an 

 insect, we are likely to find somewhere in that life history 

 some weak and vulnerable point, and that is what we are 

 after. We found that the eggs of this cabbage aphis were 

 laid in great numbers on the cabbage leaves in the field in 

 the fall. They are black, readily seen by the naked eye, and 

 laid both on the upper and on the under sides of the cabbage 

 leaves, in great numbers. They will rest right there until 



