PSO 



[ 752 ] 



PSY 



P. pule' wens (downy \ 2. Pale blue. August. 

 Lima. 1825. 



re'pens (creeping). l. Blue. July, Cape of 



Good Hope. 17/4. 



seri'cea (silky). 3. Violet. September. 



Cape of Good Hope. 1815. 



sptca'ta (long - spiked). 4. Blue. April. 



Cape of Good Hope. 1774. 



Sta'chydis (St&cYiys - leaved) . 3. Brown. 



April. Cape of Good Hope. 1793, 



stria' ta (channeled). 3. Blue. May. Cape 



of Good Hope. 1816. 



tenuifo'lia (fine-leaved). 2. White, blue. 



June. Cape of Good Hope. 1/93. 



tomento'sa (woolly). 3. Blue. June. Cape 



of Good Hope. 1820. 



verruco'sa (warted). 3. Blue. July. Cape of 



Good Hope. 1774. 



interme'dia (intermediate). 3. 



Blue. June. Cape of Good Hope. 1820. 



PSY'LLA. The Chermes, is allied to 

 the Aphis. P. pyri, Pear cheriues, 

 appears in May, not unlike a large 

 aphis, crimson-coloured, shaded with 

 black. Mr. Kollar says, when pairing 

 is over, the female lays her eggs in 

 great numbers near each other, on the 

 young leaves and blossoms, or on the 

 newly formed fruit and shoots. They 

 are of a longish shape, and yellow ; 

 and, without a magnifying glass, they 

 resemble the pollen of flowers. They 

 are called either nymphs or larvae in 

 this state (according to the extent of 

 their development) ; and, like their 

 parents, have their mouth in the 

 breast. After a few days, they change 

 their skins, and become darker, and 

 somewhat reddish on the breast, and 

 rather resemble bugs than plant-lice, 

 having the extreme point of the body 

 somewhat broad, and beset with bris- 

 tles. After changing their skins, they 

 leave the leaves, blossoms, and fruit, 

 and proceed more downwards to the 

 bearing wood and the shoots of last 

 year, on which they fix themselves se- 

 curely, one after the other, in rows, 

 and remain there till their last trans- 

 formation. 



When the nymphs have moulted for 

 the last time, and have attained their 

 full size, the body swells out by de- 

 grees, and becomes cylindrical. They 

 then leave their associates, and before 

 they lay aside their nymph -like cover- 

 ing, they search out a leaf to which 

 they fasten themselves firmly, and ap- 

 pear as if they were lifeless. After a 

 "few minutes, the skin splits on the 



upper part of the covering, anil a 

 insect proceeds from it. It is of a 

 pleasant green colour, with red eyes, 

 and snow-white wings. It very much 

 resembles its parents in spring, even 

 in the colour. After a few days, this 

 chermes has assumed the colours of 

 the perfect insect ; the head, collar, 

 and thorax, are of an orange colour, 

 and only the abdomen retains its green 

 hue. It now flies away from the place 

 of its birth to enjoy the open air. 



P. mail. Apple Chermes. This, ac- 

 cording to the same author, appears in 

 June. In September, they pair, and 

 lay their eggs, which are white, and 

 pointed at both ends, a line-and-a-half 

 long, and the fourth-of-a-line thick, 

 and become yellow before the young- 

 escapes. The apple chermes lays its 

 eggs in different places of the twigs of 

 an apple-tree ; usually, however, in the 

 furrows of the knots, and sometimes in 

 a very regular manner. The larvce 

 are scarcely escaped from the egg, in 

 the open air, when they hasten to 

 the nearest bud, and begin to gnaw its 

 scales. On the second day after their 

 birth, they cast their first skin, after 

 which they appear nearly of their 

 former shape and colour. The second 

 ; changing of the skin can sometimes be 

 ] scarcely seen at all, because the larva 

 not only puts out a thicker string with 

 ' the tubercle, but also an immense num- 

 ber of very fine entangled threads or 

 small hairs, which it turns upwards 

 over its back, a'Ad with them entirely 

 covers its body and head. In sunshine, 

 these strings look transparent, as if 

 they were made of glass, and become 

 of a greenish variable colour. Under 

 this screen the chermes are secured 

 from every attack of other insects ; for 

 no ants, mites, or bugs, can disturb 

 them in their fortification, or consume 

 them as their prey. After changing the 

 second skin, the young assume a dif- 

 ferent colour and fonn ; they now be- 

 come light green all over, the abdomen 

 much broader than the thorax, and 

 on the side of the latter, rudiments 

 of the wings are distinctly seen. The 

 third time of changing the skin comes 

 on in about eight days, sometimes 

 sooner and sometimes later, according 



