OF WASHINGTON, VOLUME XV, 1913 163 



predetermined by heredity." Bugnion, 1 studying /','///<r/m.s- Id- 

 ea xtris Bugn. and Termes redemanni Wasm. and T. hum/ Wasm. 

 states that the differentiation takes place during the embryo stage 

 for the three castes, rather than undifferentiated larvae being devel- 

 oped to the castes by the character of the food they receive. 



Observations by the writer of molting soldier Iarva3 of Leuco- 

 termes spp. and Termopsis angusticollis Walk, show that the differ- 

 entiation of the soldier caste takes place during a "quiescent ' 

 stage rather late in the life cycle. Differentiated nymphs of the 

 first and second (?) forms of L. virgin /CHS Bks. have been observed 

 in the quiescent stage, 2.5 mm. in length. At this point a brief 

 outline of the life cycle is necessary. 



In the metamorphosis of the above species the eggs hatch into 

 active, undifferentiated larvae, which develop to the various ma- 

 ture forms or castes by a gradual growth through a series of molts" 

 and "quiescent" stages. During the quiescent stage both the 

 larvae and nymphs pass through an inactive period, of compara- 

 tively short duration, isolated, lying on the side, head bent down 

 to lie on the ventral side of the body along which the antennae and 

 legs also lie extended in a backward direction. The writer first 

 observed molting larvae in a quiescent stage on August 11, 1911, 

 in a colony near Jerseyville, Illinois. During April, 1912, the de- 

 velopment of nymphs of the first and second (Lespes) forms of 

 Leucotermes flavipes Kol. and virginicus Banks was observed at 

 Falls Church, Virginia, and it was noted that both these nymphs 

 (plates vi and vn) passed through a quiescent stage in the final molt 

 to the reproductive forms; nymphs of the first form of Termopsis 

 angusticollis Walk, also pass through the quiescent stage. From 

 the first to the middle of August 1913, freshly molted pigment- 

 less soldier nymphs of flavipes in the stage preceding maturity were 

 noticeable in colonies in Virginia. On August 17, 1913, molting 

 soldier larvae were found in the quiescent stage in a colony of vir- 

 gin icus at Chain Bridge, Virginia. During the quiescent stage 

 differentiation took place. Larvae to all external appearances 

 undifferentiated or of the worker type (as shown by the head, 

 mandibles with marginal teeth and labrum of the still adhering 

 larval skin), the individuals (virginicus) being over 3 mm. in length 

 in the quiescent condition, antennae with 14 segments, develop at 

 this molt to pigmentless nymphs of soldiers with more elongate, 

 soldier-like head, and sabre-like mandibles without marginal teeth. 

 In this stage the head, mandibles, labrum, and ''menton" (Bu- 



1 Bugnion, Pr. E. La differencial ion <lcs castes chez Irs Trrrnilcs. Bull. 

 de la Societe entornologique de France, Xo. S, April, 1913, pp. 213-218.. 



-Strickland, E. H., A Quiescent Stage in the Development of T> />/>,. i 

 flavipes Kol. Jour. X. V. Ent. Soc.. vol. xix, Xo. 4, December, 1911, pp. 

 256 259. 



