OUR NATIVE TERMITES — SNYDER 503 



litermes species) . She early discovered that our arid land R. tibialis is 

 more resistant to drying than our common R. flavipes. 



In 1959, Drs. Walter Ebeling and R. E. Wagner, entomologists 

 of the University of California at Los Angeles, discovered that in- 

 festation or reinfestation after eradication of dry wood termites could 

 be prevented by treating susceptible timbers with inert sorptive dusts, 

 silica aerogel, nontoxic to humans or animals. These dusts removed 

 lipids of the termite epicuticle which caused a rapid desiccation and 

 death of the termites. Later it was discovered that water soluble 

 fluorides incorporated into the silica gels increased the effectiveness 

 with increasing relative humidities. After the wax is disrupted, flu- 

 orides can act as contact insecticides. 



In 1963 Dr. Collins, with Dr. A. G. Richards of the University of 

 Minnesota, studied in the laboratory of that university the tolerance 

 to drying of five eastern species of Reticulitermes. Included were the 

 rather desiccation-tolerant tibialis, which loses water at a consistently 

 low rate, three species that lose water relatively slowly but show great 

 variability under experimental conditions, and a species flavipes, that 

 shows a variable but relatively high rate of water loss. The desiccation 

 tolerance of tibialis, which ranges from west to east, appears to be 

 associated with a relatively effective waterproofing mechanism, a 

 well-developed cement layer, and moderate size. 



When treated to demonstrate the cement layer, species of Reticu- 

 litermes other than tibialis were found to have very small argentaflSn 

 granules in depressed areas, instead of the heavy scaly layer found in 

 tibialis. 



R. flavipes seems to have the least efficient transpiration-retarding 

 mechanism — the fact that this species may outlive species having lower 

 loss rates during drying is probably due to its large size. There also 

 were differences in the survival times in the castes. 



Transpiration resistance mcreases with age, in the absence of dam- 

 age, as does the resistance of the waterproofing to damage. This re- 

 sults in the rate of transpiration in imagoes (adults) falling to about 

 one-third the rate of teneral (not quite hardened) imagoes. 



Size appears to have no influence on the rate of loss, though it can 

 influence length of survival under dry conditions. 



Under field conditions, tibialis ranges into more arid areas than 

 the sand-dwelling arenincola, and both inhabit more arid situations 

 than flavipes. In areas inhabited by both arenincola and tibialis, 

 the former can be f omid most readily in logs and stumps on the surface 

 in spring during periods of abundant rainfall. The latter may be 

 taken at the surface during either spring or fall. In Florida, vir- 

 ginicus and hageni are found more easily than flavipes during dry 

 periods in nonf orested areas. 



