326 INSECTS. HEMIPTERA. 



head, often or eleven joints, of which the last, when their num- 

 ber is but ten, is similar to the others and not filiform ; body 

 soft. 



Many of this family, at least the females, are apterous, and sometimes their elytra 

 and wings are placed horizontally on the body. Some of them undergo a complete 

 metamorphosis. 



TRIBE I. PSYLLIDES. 



Antennae with ten or eleven joints, and terminated by two setae ; 

 elytra and wings sloping ; tarsi with two joints, and terminat- 

 ed by two hooks ; females with an ovipositor. 

 Gen. PSYLLA, LIVIA. 



Gen. PSYLLA, Lat. Chermes, Lin. 



Rostrum arising near the breast; elytra of the same consistence; 

 antennae of the same thickness or setaceous, the length of the 

 body, of ten or twelve joints, of which the last is terminated 

 by two setae ; feet proper for leaping ; tarsi with two joints, 

 and two hooks at the end of the last. 



The Psylli are small insects, found on different vegetables, and resemble in their 

 form the Aphides, but leap with agility. They feed on the juices of leaves, which they 

 pierce with their rostrum. The larvae have the body much flattened, and many fe- 

 males have an ovipositor for piercing the leaves, which produce excrescences on them. 

 Their excrements are in the form of filaments or masses of a gummy matter. 



P. a/m',Lat. Green, with the eyes brown; three spots of bright-brown 

 and yellow on the upper part of the thorax ; antennae, inferior ex- 

 tremity of the rostrum, and feet obscure brown ; ovipositor very 

 long ; nerves of the wings green. Inhabits Europe, on the al- 

 der tree. Lat. Gen. iii. 169. 

 The cottony down found on the alder in spring is the production of this insect. 



The body of the animal is also often covered with it. 



TRIBE II. PHYSAPI. 



Antennae with eight joints ; elytra and wings linear ; second joint 

 of the tarsi replaced by a vesicle, and without hooks ; me- 

 tamorphosis complete. 



Gen. THIIIPS, Lin. Lat. 



Rostrum arising from the inferior part of the head, very small, 

 composed of a sheath with two triarticulated valves, between 

 which is the sucker ; palpi short, filiform, of three joints ; 

 elytra and wings almost similar, linear, ciliated on their mar- 

 gins, and extending horizontally over the abdomen ; tarsi with 

 two joints, the last vesicular ; antennae of eight joints, almost 

 setaceous, as long as the head and thorax ; anterior segment 

 of the trunk much longer than the others ; body linear. 



The insects of this genus are very small. They live on flowers and their stems. 

 The larvae differ little from the perfect insect but in wanting elytra and wings. 



T. physapus, Lat. Black ; wings white, transparent, furnished with 

 a fringe of hairs. 1 line long. Inhabits Europe, ori 1 flowers. 

 Shaw, vi. pi. 63. 



