558 CAROLINE B. THOMPSON 



2. Dif<(inguishing characters of the five adult castes and of three 

 types of nyinphs 



Before beginning the discussion and comparison of the brains 

 of the different forms of L. flavipes some descriptions of the 

 types themselves and the means of distinguishing them may be 

 of interest. 



Forms with sex organs developed in the adult. 1. Nymphs. 

 Nymphs of the first form, with long wing pads. These nymphs 

 are most numerous in the early spring before the transformation 

 into the adult has taken place. According to Snyder they attain 

 a length of 7.5 mm. before the last molt, but they may be dis- 

 tinguished while much shorter. The color is creamy white, 

 with a pale pink or rose pigmentation of the compound eyes. 

 The hind wing pads extend back as far as the fourth abdominal 

 segment. 



Nymphs of the second form, with short wing pads. These 

 nymphs are found at the same time and in about equal numbers 

 with the long- winged nymphs. They likewise attain a length 

 of 7.5 mm. before the last molt. They may be readily distin- 

 guished from the 'first form' by the short rudimentary wing pads 

 which hardly reach the second abdominal segment. The color 

 is creamy white and the compound eyes show no trace of pig- 

 ment. 



Nymphs with no wing pads. I have never found these nymphs 

 and therefore quote from Snyder, ''Another type of substitute 

 or neoteinic reproductive form, which greatly resembles the worker 

 ('ergatoid') is developed from young larvae of the sexed forms." 



2. Adults. The true royal pair, with long wings. The true 

 winged adults are found in the nest or in the air in late spring 

 and early summer. The head and body are dark brown, of about 

 the same size as the nymphs of the first form, the long filmy 

 wings are nearly twice the length of the body. The compound 

 eyes aie black surrounded by a lighter rim of unpigmented skin. 

 The two lateral ocelli are visible as small light spots in front of 

 the compound eyes and behind the antennae. The opening of 

 the frontal or fontanel gland lies in the median line of the frontal 

 surface of the head. 



