914 EXPERIMENT STATION RECORD. 



partially effective. The eff'ective methods are divided into preventive 

 and destructive measures. Frames covered with cheese cloth or fine 

 netting and i^laced over the plants proved an efficient protection against 

 the Hies, but are only practicable with small areas and a few choice 

 plants. Tarred paper cards cut hexagonally, with a slit reaching to 

 the center, where a star-shaped cut was made to accommodate the stem 

 of the plant, were applied to the young plants on setting them in the 

 field, and i)ressed closely down to the surface of the ground. By this 

 means the female fly was unable to get at the base of the stem to lay 

 her eggs, and thus the plants were protected. Two rows of 300 plants 

 each were protected by means of the tarred cards on April 19, and on 

 May 21 less than 50 plants were attacked in each of the rows, while 

 hardly 50 plants remained standing in 4 equal untreated rows used as 

 checks. The cards were made of the paper called "1-ply tarred felt" 

 and were cut out by a stamping tool 1^ in. on the side. This method is 

 believed to afford almost complete protection to cabbages and cauli- 

 flowers. 



Destructive measures, such as crushing the eggs by rubbing the stems 

 of the cabbages with the fingers every few days and by hand picking 

 the maggots, proved effectual, but the amount of work required will 

 hardly recommend them. Two insecticidal substances proved very effi- 

 cient, a carbolic acid emulsion and soil injections of carbon bisulphid. 

 The carbolic acid emulsion was made by dissolving 1 lb. of hard soap 

 or 1 qt. of soft soap in a gallon of boiling water, to which 1 pt. of crude 

 carbolic acid was added, and the whole stirred into an emulsion. One 

 part of this was added to 30 parts of water and poured around the 

 bases of the plants, about 4 oz. being used at each application, begin- 

 ning when the plants were set out and repeated every week or 10 days 

 until the last of ]\Iay. To bring about the best results some of the 

 earth should be removed from about the plants before pouring on the 

 emulsion. In the experiments none of the cabbages were injured. 

 This method is believed to be a most successful and practicable one for 

 treating radishes, turnips, or onions, but lor cabbages and cauliflowers 

 the application of carbon bisulphid is preferred. This is applied by 

 means of a newly devised injector, consisting of a large syringe with a 

 cylinder large enough to hold about 2 qt. of the chemical and so con- 

 structed as to deposit from a teaspoon ful to a tablespoonful of the liquid 

 at every motion of the piston. The nozzle of the instrument should be 

 inserted into the soil 3 or 4 in. from the plant and pushed downward to 

 a point a little below the roots. The chemical should then be expelled, 

 the injector withdrawn, and the hole filled with earth by means of the 

 foot. One injection is usually sufficient, to be given when the maggots 

 have well appeared. The cost is about 1 ct. for every 10 plants. 



The methods designated as doubtful or but partially effective are the 

 application of gas lime, kerosene oil and sand, lime, and liquid manure 

 to the soil, and the employment of cultivation. Of insecticides helle- 



