378 



THE DICTIONARY OF GARDENING, 



ScEievola continued. 



as long as, or longer than, the tube ; corolla Jin. long, pubescent 

 outside. August I. obovate-oblong, Sin. to 5in. long, rounded 

 and obtuse at top, entire or rarely broadly crenate, on short 

 petioles. A. 2ft. 1820. An erect shrub. (B. M. 2732.) 



S. microcarpa (small-fruited), fl. violet, in a usually long and 

 interrupted spike ; calyx lobes small ; corolla hairy outside, seven 

 to nine lines long. July. fr. small. 1. petiolate, obovate, ovate, 

 or cuneate, coarsely toothed, the lower ones often lin. to liin. 

 long, the upper ones passing into sessile floral leaves or bracts. 

 1790. An erect or diftuse perennial. (L. B. C. 1327 ; B. M. 287, 

 under name of Goodenia latvigata.) 



S. pilosa (pilose). /. blue ; calyx tube pubescent ; corolla Jin. to 

 lin. long ; peduncles axillary, longer than the leaves, one-flowered. 

 May. I., lower ones petiolate, obovate or oblong, coarsely toothed, 

 2in. to 3in. long ; upper ones much smaller, sessile and stem-clasp- 

 ing, varying from oblong-cuneate to lanceolate. A. 1ft. to 3ft. 

 1841. A hispid perennial or sub-shrub. 



S. platyphylla (broad-leaved). /. white, sessile or shortly pedi- 

 cellate, in a terminal, leafy spike ; calyx lobes very small ; corolla 

 above lin. long, silky-hairy, the lobes winged. May. I. sessile 

 and stem-clasping, ovate, obovate, or oblong, entire or few- 

 toothed, lin. to liin.. or rarely 2in., long ; upper floral ones gradu- 

 ally becoming smaller. A. 2ft. 1841. An erect, hispid plant, 

 woody at base, with rigid, herbaceous branches. 



5. Plnxnleri (Plunder's). /. white, usually in axillary, peduncled 

 cymes ; calyx limb truncate-repand or obsoletely denticulate ; 

 corolla eight to ten lines long, villous within. August. I. fleshy, 

 obovate, quite entire, h. 2ft. West Indies, 1724. Stove shrub. 



6. suaveolens (sweet-smelling). /. blue, sessile, in interrupted, 

 terminal, hirsute spikes ; calyx equally flve-lobed ; corolla seven 

 to eight lines long, villous or glabrous outside, toothed or softly 

 bristly in the throat. August. I. petiolate, from obovate to 

 oblong-spathulate, quite entire, thick, the larger ones 2in. to 3in. 

 long ; upper ones smaller, or linear when on elongated branches. 

 1793. A prostrate or decumbent, hardy perennial or sub-shrub. 

 (A. B. R. 22, under name of Goodenia calendulacea.) 



SCALARIFORM. Ladder-shaped. 



SCALE INSECTS (Coccidce). These form one of 

 the most destructive families among Insects. They belong 

 to the class Homoptera, in which are also included the 

 Frog-hoppers and the very numerous Aphides or Green- 

 flies, both very hurtful to many plants. The Scale In- 

 sects have been studied by several entomologists, and 

 of late years very important advances have been made 

 in working out the life-histories of many species ; but 

 there are very wide gaps still to be filled before satis- 

 factory results can be arrived at with regard to the 

 transformations and life-histories of most of the species. 

 Among those who have done most in this field for some 

 time past are M. Signoret, in France, and Professor 

 Comstock, in the United States of America. Our British 

 species have been worked out, and the results have 

 been published in the March and April numbers of the 

 "Entomologists' Monthly Magazine" for 1886, by Mr. 

 J. W. Douglas. He has succeeded in identifying a large 

 number of species of these insects in our islands. Most of 

 them are found on wild plants; but in greenhouses some 



FIG. 44L LECANIUM HESPERIDUM (FEMALE)-O, Twig and Leaf- 

 stalk of Orange, bearing Female Scale Insects, natural size 

 6, Female magnified. 



species (see Fig. 441) infest many of the shrubs and other 

 plants to such a degree that, by the continued suction of 

 the sap, and the consequent tax on their strength, the 



Scale Insects continued. 



plants are much weakened, and ultimately die. Tho 

 females and larvae are the hurtful members of the family ; 

 while the males, when fully developed, do no harm to 

 plants. The females are by far the more numerous, and 

 the more conspicuous ; in fact, the males of even the com- 

 monest species are seldom seen, and those of a good 

 many are still unknown. They are most successfully 

 procured by collecting the larvae and pupse, which some- 

 what resemble scales, very early in spring, upon branches, 

 which, with these scales on them, should be put into 

 some secure vessel, e.g., a glass jar. 



The males are very unlike the females. They usually 

 emerge early in the year, in the form of minute flies, 

 with the head, thorax, and abdomen distinct and well 

 formed two delicate wings, six legs, and usually two 



FIG. 442. LECANIUM PERSIC^E, showing (a) Leaf with Male on it, 

 slightly enlarged ; (b) Male Flying, much enlarged. 



slender filaments at the hinder end of the body (see 

 Fig. 442). They have no mouth, and therefore cannot 

 take food in this state. They seldom live more than a 

 few days, their sole function, as perfect insects, being to 

 fertilise the females. In certain species, both wingless 

 and winged males have been found. 



Female Scale Insects are much larger than the males, 

 and they alone fully deserve the name of Scale Insects. 

 They are developed from larvae of an oval form, which 

 have three pairs of small legs (by the aid of which they 

 can crawl about), small antennae, and a beak with which 

 to bore into leaves and young stems of plants, in order to 

 suck up the sap. The larvae are protected by a scale-like 

 covering on the back. This scale is formed either by an 

 excretion from the body (in Coccince and Lecanince), which 

 increases in size as the larva grows, or also by the cast 

 skins (in Diaspince). After the larvae have fixed them- 

 selves in a suitable location on a plant, by pushing in 

 the beak, they never leave the spot. As they increase 

 in size, they undergo great alterations in structure, 

 whereby the body becomes more rounded, and the beak 

 becomes situated in the middle of the lower surface of 

 the body. The legs and antennae, and the rings of the 

 body, almost or altogether disappear. The females thus 

 at last lose all power of movement. After being fer- 

 tilised by the winged males, or, in some species, without 

 the action of the male being necessary, the females pro- 

 duce eggs, which are packed away below the scale-like 

 bodies, and are thus protected by them, even after the 

 death of the mothers. The females of some Scale Insects 

 cover the eggs also with a white coat of felted threads. 

 In certain species, the females are viviparous. 



The number of species of Scale Insects already named 

 is very large ; but of many the males, as before observed, 

 are still unknown. A large proportion live on the woody 

 kinds of wild plants, fixed to the bark or to evergreen 

 leaves, but many others select hardy cultivated plants ; 

 while others are confined, in this country, to greenhouse 



