PROC. ENT. SOC. WASH., VOL. 22, NO. 6, JUNE, IQ2O 131 



ony by the same irresistible force that induces the swarm or 

 flight." "Since the origin of the castes is due to 



intrinsic causes, (Thompson, 1017), a certain proportionate num- 

 ber of these nymphs of the second form may be produced each 

 year in long established colonies with parent first form adults, 

 they would evidently be superfluous if the original reproductive 

 forms of the parent colony were present, and might, therefore, be 

 forced to migrate," (Thompson and Snyder, 1919). 



The manner of formation of new colonies by adults of the sec- 

 ond form is not even yet definitely known. It was formerly be- 

 lieved that, at about the time of the swarm of the colonizing 

 adults of the first form, the wingless adults, accompanied by 

 workers and soldiers, left the parent colony through subterranean 

 galleries. This method of colony formation would be fairly sure 

 and rapid, avoiding most of the dangers to which the winged 

 adults are exposed when they come above ground and fly in the 

 sunlight. This would be another safeguard to insure the dis- 

 persal and perpetuation of the species. Under these circum- 

 stances, the reproductive forms would not have to establish a 

 home for themselves nor forage for food as do the adults of the 

 first form, they would be cared for and nourished by the workers, 

 their only function would be reproduction. The number of eggs 

 laid and the rate of increase would be rapid in colonies founded 

 by second form adults on account of the care and also the fact 

 that these forms are polygamous and that a large number of 

 females and a proportionate number of males are present. The 

 rate of increase in such colonies would greatly surpass, from the 

 first, that of the single pair of first form adults. 1 



In view of these previous surmises as to methods of subter- 

 ranean colonization, an observation made of a swarm of Reticuli- 

 termes mrginicus Banks at Falls Church, Va., on June 7, 1919 



1 Feytaud states that the first form adults are useful to the entire race, 

 whereas adults of the second form are merely useful to the individual colony. 

 It will be shown later, however, that second form adults may mate with 

 members of other colonies and thus escape in-breeding. 



Silvestri believed that the substitution of the "complementary" sexual 

 forms for the dealated was due to calculation on the part of the workers, 

 due to the greater reproductive powers of the larger number of "comple- 

 mentary" queens than that of a single dealated "true" queen. In that 

 event the latter was sacrificed. 



Feytaud also explains the more general occurrence of the "substitute" 

 queens in case of the species R. lucifugiis as due to climatic influence, main- 

 taining that the winged forms were very sensitive to varying conditions of 

 humidity. 



