132 PROC. ENT. SOC. WASH., VOL. 22, NO. 6, JUNE, 1920 



is of interest and value. The winged adults were observed at 

 10.45 A. M. (sun time) flying from a stump at an oblique angle in 

 a narrow mass; they flew towards the southwest. The winged 

 forms were clustered in large numbers on top of the stump (in 

 woodland) in which the colony was located, the white wings and 

 black bodies giving the mass a grey appearance. The day was 

 hot and bright and the insects were strikingly visible as they flew 

 in the sunshine. The beginning of the swarm was not observed, 

 but the flight was over at 11.15. (There was a thunder storm 

 and rain about 4 P. M.) As is usual, chinquapin (Castanea pum- 

 ila) was in first full bloom, coincident with the swarm of R. 

 mrginicus. 



When the winged adults had nearly all left the top of the stump 

 and I had finished taking photographs of the s\varm, a careful 

 examination of the top of the stump was made in search of the 

 abnormally developed winged adults or deformities which usually 

 accompany a swarm, (Snyder, 1915). With these abnormalities 

 and a few belated remaining normal winged adults were found 

 quite a few pigmented adults of the second form actively running 

 about the top of the stump in the nearly full sunlight. They 

 came out of crevices and ran about and sought other crevices, 

 fell off the stump to the ground or into a spider web at one side 

 of the stump near the base. This was possibly a manifestation 

 of or a reversion to the ancestral habit of swarming these apter- 

 ous forms have inherited the instinct to swarm but not the 

 wings and this running about is all that they can achieve. Ap- 

 parently, these adults were able to "keep their course," either by 

 vision, by tactile sense or olfactory sense perception. 



Second form adults of both sexes w r ere present; the body pig- 

 mentation in some cases was darker than usual (although just 

 as dark forms have been found previously) and the compound 

 eye was more pigmented and prominent than is normally the 

 case. 



Several theories may be propounded to account for the presence 

 of the second form adults outside of the parent colonies or the 

 "pseudo-flight:" 



1. These may be in reality abnormally developed first form 

 adults. The shortness of the wing-pads and pigment would ren- 

 der this doubtful since first form adults do not attain pigment 

 till the wings are fully expanded. However, there are other 

 characters, both external and internal, which have definitely dis- 

 proved this conjecture. The chief external character by which 

 it can be proved that these are second, and not first form, adults 

 are the meso- and meta-thoracic tergites. In the first form they 

 are in two main parts, whereas in the second form they seem to 



