410 BRITISH GENERA, IN THE 



ceous, inserted on the advanced margin of the front, between the 

 eyes. Simple eyes, usually three, placed in a triangle between tbe 

 eyes, before the antennae. The prothorax is a distinct, rather 

 ample segment, with free motion ; the propectus, deeply notched 

 to admit the mouth. The pterothorax is composed of nearly equal 

 segments, or the anterior smaller. The abdomen of ten segments, 

 the 1st of which (metapodeon, — Newman,) is concealed below by 

 the postpectus. Wings, usually four; linear, narrow, not folded 

 nor reticulate ; the nerves and margin fringed with long hairs, 

 which diverging in flight, compensate for the smallness of the 

 membrane. The upper pair are of stronger consistence, some- 

 times true elytra. The legs are short, each pair distant, the 

 middle most, the hind pair least so. The feet two-jointed, with 

 a vesicular tip, without claws. The larva resembles the perfect 

 insect, but has a softer body, with the mesothorax and metathorax 

 distinct : the mouth is almost alike, the antennae and legs shorter ; 

 there are no simple eyes, and the compound are replaced by con- 

 glomerate eyes. The pupa resembles the perfect insect, but the 

 articulations of the limbs are obscured by a film, and the wings 

 enclosed in short fixed sheaths. The antenna? are turned back 

 on the head, and the insect, though it moves about, is much more 

 sluggish than in the other states. 



In the first family the females are oviparous. I have neg- 

 lected to observe whether it be the case in the others ; but the 

 structure of the borer leaves little doubt on this point. They 

 feed on vegetable juices, and are often extremely injurious 

 from their multitudes. It is probable that many of them have 

 several broods in the year ; indeed Passerini expressly asserts 

 it. Others appear in the perfect state only for a short time, 

 during the flowering season of a particular plant. 



The order Thysanoptera seems sufficiently distinguished 

 from Hemiptera by the distinct palpi and the broad external 

 maxillae; from Orthoptera, by the internal capillary mandibles, 

 and the maxillae, which are almost fixed, and have not the 

 galea. The name proposed is taken from the plume-like fringes 

 of the wings. From the way in which the alary segments are 

 joined, there appears to be but one complete system of muscles 

 for both pair of wings. 



