5G 



HARDTTICKE'S SCIENCE-GOSSIP. 



milkwort always more or less present, though some- 

 times not in a strongly-marked degree, upon the 

 base of the corolla. The pure blue and pure pink 

 are found in the tall, strong, many - blossomed 

 hedgerow form, as well as in the short, spreading 

 plant of hill-sides and heaths; but the white, so far 

 as my experience has gone, in the latter form alone. 



Oxalis acetosella is wholly white at times, though 

 usually the delicate veins of the petals are exqui- 

 sitely lilac in their colouring. But it also alters in 

 the other direction, and is found in the lanes of 

 Treflach, near Oswestry, of a rich and full pink. 

 Anthyllis vulneraria has occurred on the Capstan 

 Rock at Ilfracombe, of a pale cream-colour, tinged 

 with blue. That being the first specimen of the 

 plant I met with, it was with surprise 1 afterwards 

 found how widely it differed lrom the ordinary 

 yellow flower. Symphytum officinale, it may be 

 noted, occurs abundantly around Oxford in two 

 kinds — one of the usual red and purple, and the 

 other with flowers entirely of a yellowish cream- 

 colour. 



Oxford. W 



NOTES ON GREENHOUSE PARASITES. 



VERY many there be, who are possessed of con- 

 servatories and greenhouses, who are perfectly 

 unacquainted with the various kinds of injurious 

 insects that dwell in them, more especially those 

 which feed on the life-juices of the plants, on which, 

 if they are left undisturbed, they will in due time 

 cause their annihilation. Generally all is left to 

 the gardener, who knows the various devices that 

 are requisite for restoring to health the sickly plant. 

 A professed gardener undoubtedly is a luxury ; but 

 alas, what does the poor amateur, who may have 

 for the first time undertaken the care of a green- 

 house, know about these aggravating insects ? 

 When he sees on his plants a curious and unknown 

 object, he suspects it is injuring! them — at least he 

 judges so from their unhealthy appearance. Having 

 said this much by way of an introduction, I shall 

 now proceed to give a brief description of these 

 parasites. I shall not, however, allude to the 

 Aphides, the most mischievous tribe of all, as in the 

 columns of this journal have appeared from time to 

 time various notes on them. The next greatest pest 

 is the Thrips Adonidum (figs. 29 and 30), which in the 

 summer season abounds on every out-of-door flower ; 

 as, for instance, the blossom of the Bindweed, Dande- 

 lion, Rose, &c. This insect is minute, its colour 

 being generally black or rusty ; the abdomen is long 

 and pointed, aud its wings are of a dirty white ; the 

 antennae and legs are yellowish, the extremity of the 

 former being black. The larva and pupa are of a 

 pale yellow, and very unsightly to behold, especially 



when seen under the microscope. These, as well as 

 the mature insect, are found on the underside of the 

 leaves they prey on, which, having pierced, they 

 extract the juice, depositing it in black spots over 

 the leaf. This being of a glutinous nature, fills the 

 pores, and afterwards the leaf turns pale yellow or a 

 sickly green, and falls off. In March the full-grown 

 insects are found collected together, and as the 

 warm sun of spring comes forth, they depart abroad 

 to raise a household for themselves. Another 

 species, called T. ochraceus, feeds on fruit, and does 



Fig. 2". Red Spider (Acarus tellarlus), x 30. 



great damage to it by piercing the stalks, and 

 causing the fruit to fall off before it is ripe. In 

 appearance it is similar to the above-mentioned 



^^ 



Fig. 2S. Mealy Bag, x 20. 



one, but is more hairy. The next destroyer appears 

 under the classical name of Coccus, or scale insect 

 (figs. 31 and 32). Those generally found fixed on 

 the stem and leaves of the plant are females. They 

 are shield-like in shape, being convex above and 

 flat or concave below ; have six small legs ; and as 

 the insect increases in age, these grow into their 

 bodies. On the underside of the insect is a sucker, 

 with which it pierces the cuticle of the plant, so as 

 to obtain the desired food. Soon after the female 

 lays her eggs she dies, aud her body becomes 

 covered with a long white woolly substance, that 

 guards her eggs during their incubation. The 

 " Cocci " are of various colours, the darkest being 



