ON ORCHIDS. 



621 



attack by any pests, animal or vegetable, which is seldom vouch- 

 safed to most popular plants, is certain. Of late years, however, 

 several formidable pests have threatened the Orchid-grower, and 

 in some collections much damage has actually been inflicted. 



The most destructive of insect pests 

 amongst the newcomers is a tropical 

 beetle, scientifically known as Xyle- 

 borus perforans. The genus is un- 

 represented in this country, but in 

 the sugar - cane districts this same 

 beetle occasions the planter not a 

 little anxiety. The generic and 

 specific names give sufficient clue to 

 its propensities, • which are to tunnel. 

 Dendrobium Phalcznopsis are the 

 plants usually selected, and these are 

 Fig. 402. — Dendrobium Beetle, attacked by means of the pseudo- 

 and Portion of Plant bulbs. Having gained access, the 



SHOWING PERFORATIONS. beetleg practicall tunnd the st 

 (Much magnified.) ■ . 1 , . , 



causing the plants to have a most 



(By permission of the Board of % i*Ii 1 



Agriculture.) unhealthy appearance and not . in- 



frequently to die. The beetle (Fig. 



402) is about 2^mm. long, and chestnut-brown. The larva (Fig. 



403) is white and footless, and is also capable of much mischief. 

 Dendrobiums, therefore, which show signs of decay without a cause 

 being readily assigned for it, should be carefully examined, and if 

 the small perforations are noticed in the growths (Fig. 402), the 

 portions must be cut away ; for it is better to risk the check that such 

 is sure to cause than the utter destruction of the plant attacked. 



In Cattleyas there is a species of fly (Isosoma orchidearum) 

 which occasions a lot of damage. This insect deposits its 

 eggs in the eye of the young growth when 

 the plant is in a- dormant state. As a con- 

 sequence, the growth does not advance much 

 above iin., swells in the centre, and generally 

 exhibits a stunted appearance. If this growth 

 is cut aff at the ba,se and split open, there 

 will be disclosed from three to seven yellowish 

 maggot-like creatures. After eating a large 

 hole in the young growth, they become pupae, 

 and eventually emerge as perfect flies. They 

 should be destroyed as soon as seen. Fumiga- 

 tion with a vaporising insecticide will effectually 

 settle them before they have time to deposit 

 their eggs. The roots, too, not infrequently, Fig. 403.— Grub of 

 are pierced by the insects, and a warty growth Dendrobium 

 results. The grubs should be picked out Beetle. 



with a stout needle. 



