10 FABMEES BULLETIN 837. 



With concerted action on the part of growers in following out 

 these methods the insects may be held in check in regions where 

 asparagus does not grow wild in too great profusion; elsewhere in- 

 secticides must be used. It is well in any case to employ insecticides 

 after the cutting season, since if the insects are destroyed at this 

 time their numbers the next year will be lessened. 



THE BRUSHING METHOD. 



A simple and inexpensive method of killing the larvae in hot 

 weather is to beat or brush them from the plants with a stick so that 

 they wiU drop to the bare ground. The larvse are delicate creatures, 

 and, as they crawl very slowly, few are able to regain shelter of the 

 plants, but die when exposed to the heated earth. 



DUSTING WITH ARSENICALS. 



An arsenical, applied dry mixed with flour, as for potato beetles, 

 answers weU as an insecticide, destroying beetles as well as grubs, 

 and is of value on plants that are not being cut for food. A mixture 

 of arsenate of lead and air-slaked lime, or plaster, 4 pounds of the 

 former to a barrel of the latter, is recommended. For satisfactory 

 results the lime and arsenical must be applied at frequent intervals, 

 or as often as the larvse reappear on the beds, 



SPRAYING WITH ARSENICALS. 



Arsenate of lead has given better results in spraying than any other 

 arsenical. This insecticide has come into very general use in recent 

 years and has superseded Paris green and other arsenicals for the 

 control of leaf -feeding beetles, such as the potato beetles and asparagus 

 beetles. It is less harmful to growing plants and less likely to burn the 

 leaves, adheres better to the foliage, is less troublesome to prepare, 

 and is more effective.^ In addition the spray, on drying, leaves a 

 white coating on the plants, so that it can be readily determined which 

 plants have been treated and which have not. 



Two pounds of dry lead arsenate, or 4 pomids of lead-arsenate 

 paste, to 50 gallons of water or Bordeaux mixture will make a solution 

 of sufficient strength to destroy asparagus beetles and their larvae. 

 The number of sprayings to be applied depends on local and seasonal 

 conditions. Sometimes a single spraying at the proper time will 

 suffice, but occasionally two or three applications are necessary, 

 especially if rainfaU intervenes. The adhesiveness of the spray 

 material is promoted by the addition of about the same amount, by 

 weight, of resin-fishoil soap as of the arsenical used. 



iln Pennsylvania a comparative test was made of the value of Paris green and arsenate of lead, showing 

 that not more than 50 per cent of the insects were killed when Paris green and lime were used, while 90 per 

 cent were killed with arsenate of lead; and when resin soap was added to the arsenate of lead to make the 

 latter adhere more closeh to the plants, n^Z of the insects were killed on 50 plants treated. In the last 

 experiment the arsenate of lead was used at the rate of 2 pounds to 50 gallons of water, with 5 pounds of resin 



