VEGETABLE INSECTS 



181 



the soil is pressed away a little, it will drop the eggs next to 

 the stalk. It may lay several near one cabbage plant. These 

 hatch into the white maggots which burrow up and down the 

 roots until finally the fine roots are all withered and killed. 

 Then the plant wilts above and dies. After about three weeks 

 the maggots on the roots become mature, and then they 

 change into what we call pupae, which are dark colored, 

 short, and oval. From these the adult fly comes out ready 

 to deposit its eggs for another generation. At least on Long 

 Island there are three generations of these flies during the 

 season. During the autumn it is probable that the adult 

 fly hides away under rubbish to pass the winter, appearing 

 again in the spring; but it is certain that the puparia pass 

 the winter, and from them come the adult flies. The stages 

 in which it lives over the winter are passed in the field un- 

 derneath the rubbish that is left there or about the edges of 

 the field underneath whatever rubbish they can find. 



The question arises, how can we protect cabbages in the 

 field from this insect? It is impossible where cabbages are 

 grown on a large scale to treat each individual plant accurate- 

 ly with any insecticide w^hich will be very effective. We have 

 used the carbolic emulsion, which is very practicable in a 

 garden; but in a field on a large scale one is forced to use 

 tarred paper pads. Tarred pads first came into use in Wis- 

 consin, being introduced by Professor Goff. These bands are 

 hexagonal in shape, and in the middle of each there are 

 little slits, as well as a slit to the edge, which allows one to 

 bend it a little and slip it around the cabbage plant. You 

 would be surprised at the number that one man can put on 

 in a day and at the small expense involved in treating a large 

 field of cabbages. It is a practical thing. In putting them 

 on, one should press them down so that the insect is pre- 

 vented from laying its eggs on the soil or at least so that 

 the eggs can be laid only on top of the paper pads, where 

 they dry up and fail to hatch. That is about the only prac- 

 tical method of fighting this cabbage maggot in the field on 

 a large scale. There are some things you can do in addition 

 in the matter of cleaning up rubbish at the end of the season, 

 especially around the edges of the field, in order to destroy 



