ROUNDHEADED APPLE-TREE BORER. 31 



these two methods have received special consideration. Tests were 

 made of the effects of penetrating liquids of an irritating or poison- 

 ous nature when applied to the bark beneath which borers were 

 feeding, of gaseous and poisonous liquids injected into the bur- 

 rows, of sticky substances applied to the trunks of trees for the pur- 

 pose of entangling the adults during their egg-laying activities, and 

 of killing the adults by the use of poisonous sprays. Studies were 

 made also of the distance which female beetles may fly in search of 

 trees in which to oviposit, with the idea of determining the possi- 

 bility of preventing the infestation of orchards by destroying near-by 

 breeding places. These various tests are described in detail below 

 under their various headings. 



WORMING. 



The labor of removing borers from trees with a knife and wire is 

 not relished by the majority of orchardists, and yet the difficulties 

 and expense of the task are less than in many other necessary opera- 

 tions in dealing with insect and fungous enemies. Two men, on an 

 average, with an insignificant expenditure for tools and material, 

 should worm 500 trees in a day and obtain as high a percentage of 

 control as ordinarily results from a spraying operation against the 

 codling moth or San Jose scale. Not only does a thorough worming 

 of an orchard rid the trees of the borers present at the particular time 

 but it insures a decreased number of borers for the following one or 

 two years. As is shown on pages 20 to 24, by preventing adult borers 

 from developing within and adjacent to an orchard a reduction may 

 result of about 75 per cent in the number of borers that will attack the 

 orchard the ensuing year. 



The process of worming is well understood ; the best tools for the 

 purpose being a garden trowel for removing the earth and litter 

 about the trees, a pocketknife with a long, sharp blade, a narrow 

 chisel for securing borers that have penetrated deep into the wood, 

 and a piece of slender wire (PL IX, B) about a foot in length with a 

 sharp hook bent at one end and a tag or bit of conspicuous cloth at- 

 tached to the other end to safeguard the wire against loss. These 

 tools may be carried conveniently in a small fruit basket. The 

 writer found that worming can best be done by two men working- 

 together on opposite sides of the tree. With a little practice, one 

 becomes quite adept at locating burrows and hooking the borers 

 from their retreats. After a little skill has been acquired the chisel 

 will have to be used only on rare occasions when deep burrows in the 

 wood are found to be so crooked that the wire on being inserted will 

 not follow the openings. 



Worming should be done as soon as possible after the last eggs 

 of the year have hatched, as young larvae usually feed rapidly and 



