the monthly bulletin. 



257 



devised by J. R. HortoD of the United States Department of Agricul- 

 ture, and was published in Vol. 5, No. 11, of the Monthlj Bulletin, to 

 which those interested are referred. The second type of barrier is 

 exemplified by the corrosive sublimate Kami, which is also described in 

 Mr. Horton's article above referred to. While it is quite effective, its 



cosl is probably prohibitive for orchard 

 work, and there is also an element of danger 

 in its use which must qo1 be overlooked. 



In m\ opinion, however, judging from 

 experiments carried on at the southern 

 branch of the insectary at Alhambra, and 

 which it must be admitted arc yel too young 

 to justify final conclusions, the poisoning 

 method will supersede entirely the barrier 

 method For the control of this pest in the 

 orchard. ■ Poisoning was successfully used 

 1>\ both Professor Woodworth and Mr. E. R. 

 Barber, of the United States Department 

 of Agriculture, in municipal work, and in 

 our experiments we have made use of the 

 formula which was proven must satisfactory 

 by Mr. Barber. The secrel of this method 

 lies in the use of a poison which is so dilute 

 entrance hoii s and poison that the worker ants will carry it to the nest 



in large quantities and feed it to the egg 

 laying queens and larvaj, which succumb to its effects in two or three 

 weeks. A strong poison will destroy the workers before they are able 

 to carry it to the nest, with the result that the colony continues to thrive 

 at the expense of the on-hard. 



The Bureau of Entomology formula is as follows: 



"Prepare a sirup : 



Granulated sugar — 15 pounds 



Water 7 pints 



Tartaric acid (crystallized) $ ounce 



Boil for 30 minutes. Allow to cool. 



Dissolve sodium arsenite (C.P.) J ounce 



In hot water 1 pint 



Cool. Add poison solution to sirup and stir well. Add to the 

 poisoned sirup : 



Honey lj pounds 



.Mix thoroughly. 



I'ii:. 71. — Poison bag before 

 folding showing position of 



"From the results so far obtained, the careful preparation of the 

 poisoned sirup can not be too highly emphasized. Very accurate bal- 

 ances are necessary for the weighing out of the poison and the tartaric 

 acid. This is especially true when small quantities of the sirup are 

 prepared." 



As a container for the poisoned sirup for use in orchards we have 

 found the paraffine paper bag to be best. < >ne pound or one-half pound 

 paper bags with Hat bottoms should be secured and holes should be 

 made as in the illustration. These can best be made with a common 

 leather punch, several bags being punched at one time. Then they 

 should be dipped, closed, in hot paraffine and opened before cooling. 

 A small .piece of clean sponge may be placed in each bag, although this 



