2 BULLETIlSr 108, UXITED STATES I^ATIO^ATL, MUSEUM. 



GENERAL STRUCTURE. 



The termites are Neuropteroid insects which live socially in mod- 

 erate to large colonies. From their gregarious habits and pale color 

 of most forms they are commonly called "white ants," They exist 

 in two or three castes- — usually a soldier with modified head, usually 

 a worker caste, and the winged caste which is always present. The 

 \vinged caste consists of the male and female adult insects. The sol- 

 diers occur in all genera except Anoplotermes, and originate from 

 young of both sexes; occasionally they show traces of wings. The 

 worker caste occurs in all except the Kalotermitidae ; they are small, 

 wingless, and usually blind. There are immature stages for all these 

 castes. 



After a flight the winged female breaks off her wings and starts a 

 colony. She becomes enlarged, often greatly, with eggs, and is now 

 known as the queen or "true" queen or queen mother. In some 

 species these "true" queens are very rare, or at least hard to find. 

 Sometimes nymphal forms become fertile without acquiring wings; 

 they vary in number. Females of one of these forms may be present 

 in colonies with "true kings" or m^ales. Thus it is seen that each 

 colony of termites may have from five to seven forms as well as 

 young. This will be discussed in detail under biological notes. 

 However, for systematic purposes, the winged form preeminently 

 represents the species. The soldier is usually more or less charac- 

 teristic for each species, and in several genera the species can be- 

 traced almost as well by soldiers as by adults. 



The adult insect has a head nearly or quite as broad as long, 

 flattened, truncate in front, rounded behind. The compound eyes 

 are on the side nearer to the anterior than to the posterior end. 

 In front of the eye is the antenna! fossa, from which arises the slender, 

 moniliform antenna, of 12 to 25 or more joints; the first longer than 

 the others. The clypeus is broad; in some forms v/ith a median 

 line. Below the clypeus is a labrum of characteristic shape in each 

 genus. The mandibles are short and the inner edge with several 

 teeth, but the two jaws are not toothed alike. The maxillae end in 

 two corneous curved points; the maxillary palpi are five-jointed, the 

 basal two very short; the lip is small with short, three-jointed labial 

 palpi. The gula is large and of various shapes, according to the 

 genus. In most forms there is an ocellus close to each eye, and in 

 fully one-half the species there is a more or less distinct median 

 aperture on the face, called the "fontanelle" or "fenestra," which 

 is the opening of the frontal gland ^ whose secretion is utilized for 

 defense. 



1 Thompson (1916) suggests that the frontal gland may have arisen phylogenetieally from the ancestral 

 median ocellus, which is now lacldng in the termites. The frontal gland is an actual morphological struc- 

 ture, wliile the term "fontanel" may be used by some authors to mean the area above the gland and by 

 others as the gland opening; that is, "frontal driise" and "glande frontale," as well as "fontanel." 



