OrtheziincB. 421 



five a day for a period of six weeks or more ; by which time the parent is ex- 

 hausted and dies, and the earliest hatched larvae have commenced ovipositing 

 on their own account. The length of life of a single insect is therefore about 

 fifteen weeks ; but, as it commences to produce larvae at the ninth week, there 

 may be five generations within the year. This fecundity is more or less in- 

 dependent of the attentions of the male insects, which appear only at irregular 

 intervals. It is doubtful whether a generation of males is produced even once 

 a year. An interval of four years occurred between the first and second 

 observed broods. On both of these occasions the male insects occurred in 

 enormous numbers, hovering in the air like gnats, the silky tufts on their tails 

 glistening in the sunlight. 



The 'Lantana bug' is one of, if not the most, resistant of all scale-bugs 

 towards insecticides. It is therefore a useful subject upon which to test various 

 treatments. An insecticide that will kill Orthezia can be guaranteed against 

 any scale pest. It is remarkable that the half-grown insects will often survive 

 treatment that has successfully destroyed the younger and older individuals. 

 Treatment with hydrocyanic acid gas is eftective in the case of isolated plants, 

 and in confined spaces such as Wardian Cases and greenhouses. The gas 

 treatment, however, though really very simple, rec^uires considerable care in 

 application and is subject to certain dangers. It cannot therefore be 

 recommended for general use without previous demonstration by a trained 

 operator. Spraying is the next best measure. But however thoroughly this 

 work may be done, a certain proportion of the insects will be sure to escape, 

 and the process must be repeated at intervals until the pest has disappeared. 

 I have found that mixtures of which soap is the principal component are more 

 efficaceous against Orthcsia than any other kind of spray. Besides killing the 

 insect, the soapy matter blocks the aperture of the ovisac, preventing the 

 emergence of the young larvae. It should be noted that the insects will remain 

 attached to the plant for a long time (sometimes for two or three weeks) after 

 they are dead. Examination with a hand lens is often necessary to determine 

 whether the application has been successful or not. If the legs remain rigid 

 and do not move when the insect is disturbed, it may be presumed to be dead. 



With regard to the mode of distribution, the young larvte of all scale insects 

 are very easily transported from one place to another. They are minute and 

 active and can exist for several days without food. The young Orthezia is 

 particularly resistant in this respect. They may crawl on to the feet of birds, 

 or even on to larger insects that may be resting on the bug-infested plant, and 

 may be conveyed in this manner to a considerable distance before being dis- 

 lodged. They may be brushed off and carried away on the clothing of passers- 

 by. The rough cumblies worn by coolies are particularly liable to carry the 

 infection. Wandering cattle also are unconscious distributors of the pest. The 

 young insects are so light that they may be transported by wind. The con- 

 spicuous way in which the pest is spreading along the sides of the railway 

 track points to the supposition that they are carried along by the draught of 

 passing trains. Running water is another fertile source of distribution. An 

 infested plant growing on the banks of a stream or river is sure to shed some of 

 the insects into the water, when they may float down for miles before effecting 

 a landing. The interchange of garden plants is a source of danger. It must 

 have been in this way that the pest obtained a footing in Ceylon. This intro- 

 duction occurred before the establishment of a Quarantine Station at Colombo. 



