Carpenter et al.: Mosquitoes of Southern U. S. 25 



lateral area of the head is occupied by the large compound eyes; ocelli are 

 lacking. In the adult descriptions in this book the dorsal part of the head 

 posterior to the eyes is termed the occiput, and that portion projecting for- 

 ward between the eyes, the vertex. The jrons lies between the bases of the 

 antennae and joins the anterior margin of the vertex. The vestiture of the 

 occiput and vertex consists of scales and setae of various types and colors 

 and is often used in identification. The frontal tuft, a group of setae arising 

 from the anterior part of the vertex and extending forward over the frons, 

 is well developed in Anopheles, and its color differences can be used as an 

 aid in separating some of our dark-winged species. 



The dypeus is a short, usually nude, snout-like projection just anterior to 

 the frons. It is longer than broad, with distal margin rounded, in the tribes 

 Anophelini and Culicini, but wider than long, with distal margin somewhat 

 trilobed, in the tribe Megarhinini. 



The antennae are a pair of long, slender, 15-segmented structures arising 

 on either side of the frons between the eyes. The first segment, the scape, 

 is small, cylindrical, and hidden beneath the globular second segment, the 

 torus. The remaining 1 3 segments are filamentous and are collectively re- 

 ferred to as the flagellum or individually as the flagellar segments. Each 

 flagellar segment bears a whorl of hairs, usually long and bushy in the males 

 and much shorter and sparser in the females (Fig. 8).i 



The ynaxillary palpi are 5-segmented (the first segment very short) and 

 originate at the anterior margin of the head just below the clypeus. They are 

 important to the taxonomist, not only because they may bear rings or patches 

 of scales of contrasting color, but also because of sexual modification and 

 striking variations in some genera, subgenera, and species. In Culicines the 

 palpi of the female are more or less straight, much shorter than the pro- 

 boscis, and usually smooth-scaled. The male Culicines usually have densely- 

 haired palp' longer than the proboscis, each with the last two segments angled 

 upward and tapered to a point.- These long, bushy palpi, together with the 

 bushy antennae, usually make it comparatively easy to distinguish the sex 

 with the naked eye. In the Anophelines the palpi of the fema'es are straight 

 and, with the exception of the exotic genus Bironella, about as long as the 

 proboscis. The palpi of male Anophelines are about as long or longer than 

 the proS(^scis and usually less conspicuously haired than those of Culicines. 

 The last two segments of each are somewhat ankylosed. flattened, analed 

 upward, and rounded at tip. Differences between the palpi of Culicines and 

 of Anophelines are illustrated in Fig. 8. 



The mouthparts, consisting of a conspicuous, greatly elongated lower iip 

 or labium, with its enclosed piercinq and sucking structures, are collectively 

 known as the proboscis (Fig. 9). The labium is a sheath-like organ which 

 terminates in a pair of small, approximate lobes, the labella. As well as 



1 Of the species occurring in the southern states, the males of Deiiioceriles cancer, 

 Uranotaenia lowii and lV\)eom\)ia spp. have antennae similar to those of the females. 



2 In the southern states, the palpi of the males are similar to those of the females 

 in Deinocerites, Vranoiaenia, Wyeomxila and Acdes cinereus. 



