10 BULLETIN 1232, IT. S. DEPARTMENT OF AGRICULTURE. 



tacked. This cable carried two spare wires (neutrals), not used. 

 This was in the crossover wells, i. e., away below the floor of the 

 lock chamber. In this case the cables have a certain definite twist 

 and the termites followed the two spare, unused wires, and kept 

 entirely away from the wires carrying the high-tension current. 



It is the writers' opinion that much more damage was done, but 

 that it was sporadic in nature, so that it was entered in the records 

 only as repair work, of which there is always plenty. 



The damage was confined particularly to one small section along 

 the center wall of these locks, between two or three of the light 

 posts. The duplex cable, which measures 9 by 19 millimeters on 

 cross section, runs through conduit pipes that are 34 inches in 

 diameter (PI. V, A). The particular type of injury is well illus- 

 trated in the photographs (PI. V, B-G). As a rule, the termites had 

 their galleries attached to the lead-covered cables. At places, for 

 some reason or other, they worked into the lead, perforated it, and 

 then traveled between the two insulated wires (PL V, D), there 

 being some space between these wires. As this space is not wide 

 enough, they chewed away the insulating material, including the 

 rubber (PL V, D, E). The hole through the lead is usually en- 

 larged on the inner surface. They travel thus between these two 

 wires for spaces of a foot or so, sometimes only for a few inches, and 

 then emerge again and build the galleries along the outside of the 

 lead cable. It is estimated that there was a hole every foot or so 

 (PL V, Z>, C, G). The particular damage to the service is due to 

 the entrance of moisture through these holes. 



In another instance these termites cleaned off on the duplex cable 

 a. section about 15 inches in length along the narrow edge, thus giving 

 the cable a flat surface and making it look very much as if it had gone 

 through a shaper machine, excepting that the surface was not very 

 smooths (PL V, E.) 



The center wall of the locks consists of a main tunnel near the sur- 

 face, extending only as far as there are lock gates. Since the center 

 wall is prolonged farther than the two side walls, the outer part has 

 no tunnel, but only manholes, some of these large recesses being big 

 enough for a man to walk around in. Each manhole feeds two lamp- 

 posts. It was at one of these that most of this damage was noted- 

 It was found that in these manholes and recesses plenty of moisture 

 was usually present, and in most instances some of the timber was 



Description of Plate V. 



Injury to lead-covered cable by the termite Coptoterm-es wiger at Mieaflores 

 Locks, C. Z. : A, View in one of larger manholes, in center wall of locks,, showing- ends of 

 3j-inch conduit pipes and duplex lead-covered cable coming out of these. Across second 

 (middle) pipe is seen a termite gallery which started in the pipe above and is completely 

 separated from the- wall. Below middle pipe is seen continuation of it. about one-half inch 

 suspended. Wandering galleries along concrete wall coalesce in places or become enlarged, 

 forming small cavities in which termites congregate. Flashlight photograph by E. St. 

 Clair Clayton, November, 1921. B, Four typical samples. In one case is seen a large area 

 chewed away with part of insulation also gone. These are duplex telephone 7-strand ca- 

 bles. Holes occurred about every foot or so, the termites getting between the two insulated 

 wires and traveling in this space, eating away part of insulation. Duplex cable meas- 

 ures 19 by 9 millimeters. C, Five pieces of duplex lead-covered telephone cable, showing 

 holes made through lead sheathing by termites. D, Part of cable covering opened out 

 to show runway of termites between two insulated wires, parts of Insulation eaten away 

 to rubber coverings and sometimes even this eaten away. E, Part of lead covering chewed 

 away, also portion of insulation. In the second case termites chewed away a flat channel, 

 about 12 inches long, along edge of lead cable. F, Another view of D, showing eaten- , 

 away insulation running whole length of wire in both cases and in one with more ex- 

 tended injury at site of opening. G, View of D and F, with only a portion of lead cover- 

 ing laid open, showing boring as first discovered. 



