ARTICÜLATA. 193 



pupae, and instead of respiring through the posterior extremity, they 

 have two horn-like tubes on the thorax for this purpose. The pupae are 

 active, but do not take food. The entire period required for the trans- 

 formations is about three weeks. Culex {pi. 77, figs. 95, 96), Anopheles 

 {fig. 94). 



The TipulidcB are an extensive family, which bear a considerable 

 resemblance to the Culicidae, on account of their slender body and feet. 

 The rostrum is short, robust, and ending in a pair of fleshy lips ; the palpi 

 are generally four-articulate, and turned back. The abdomen of the male 

 is often thickened at the tip, the antennae have in general from fourteen 

 to sixteen articulations, those of the male being often verticillate or 

 pectinate. The larvae of some are aquatic ; some live in the ground, 

 where they destroy the roots of grass ; some in fungi or decaying 

 matter, and some in galls. The minute but destructive insects of 

 the genus Cecidomyia (Hessian fly) belong to this family. There are 

 several sub-families which Westwood names Chironomides, Ceci- 

 domyides, Mycetophilides, Tipulides, and Bihionides. The genera figured 

 are, Chironomus (pi. 77, fig. 118), Anisomera (fig. 119), Ctenopliora 

 (fig. 120), Fsychoda (fig. 121), Mycetophila (figs. 122, 124), Bihio 

 (fig. 123). 



The StratioinydcB are generally gaudily colored ; they are found upon 



• flowers, and have the body usually depressed, and the scutellum often 



spinose. The larvae are aquatic or terrestrial, and the pupa is formed 



within the skin of the larva. Stratiomys (pi. 77, fig. 117), Clitellaria 



(fig. 110). 



The TahanidcB have the eyes large, the mouth well developed, that of 

 the female having six and that of the male four piercers. The labium is 

 fleshy, with the end lobed ; and the palpi have two articulations, of which 

 the second is long. Tahanus (T. tropicus, fig. 97, T. bovinus, fig. 98) 

 has the third articulation of the antennae excised upon one side. The genus 

 contains some of the largest of the Diptera, and from their size, number, and 

 the perfection of their oral organs, they are a great pest to cattle when 

 numerous. The males frequent flowers, the females alone sucking blood. 



The Bombyliidce (Bombylius, pi. 77, fig. 87) resemble certain bees, and 

 the analogy is preserved by the buzzing sound they make in flying. The 

 rostrum is very long, and projecting in front, and with this they suck 

 flowers without alighting. Their wings stand horizontally, and their flight 

 is very rapid. • 



In the EmpidcB (figs. 92, 93) the body is narrow, the head small 

 and round, with a distinct neck, the wings are large, and the feet 

 generally long. The males generally live upon honey, and the females 

 upon the juices of insects which they take on the wing with the aid of 

 their feet. 



The AsilidcB include several large predaceous Diptera, with a slendei 

 bristly body, a depressed head, bearded below, and a robust thorax. They 

 fly with a buzzing noise, and take other insects upon the wing. The larvae 

 feed upon roots. Dioctria (fig. 88), Asilus (fig. 89). 



397 



