26 



The Soft or Brown Scale. 

 (Lecaniwm liesperidum Linn.) 



This is perhaps the most common and widely distributed of the scale- 

 insects, being found in the four quarters of the globe, and although not 

 infrequently occurring in large numbers, still 1 have never known of a 

 single instance where a tree or plant has ever been destroyed by it. 

 Its general effect is to weaken or stunt the infested plant and to ren- 

 der it black and unsightly by reason of the black fungus which always 

 accompanies its attacks. 



This scale-insect is quite a general feeder, infesting wild trees and 

 plants as well as cultivated ones. I have found full-grown specimens 

 on the following trees and plants: 



Lombardy Poplar, Grape, Loquat, Eubber Tree (Ficus macropliylla), 

 Ash, Euonymus, Maple ( Acer dasycarpum), Bhamnus crocea, Heteromeles 

 arbutifolia, Rhus integrifolia^Te^er Tree (Schinus moll-e), Willow, Apri- 

 cot, Citrus trees, Fig, Locust, English Ivy, EDglish Holly, Eose, Calla 

 Lily, Oleander, and Pittosporum. It infests the leaves and green bark, 

 but is very seldom found upon the fruit. 



This species brings forth its young alive, although when first ex- 

 cluded they are still enveloped in a very thin sac, which in a short 

 time is cast off. They remain for several days beneath the parent and 

 then start out for themselves. The greatest number of larvre and 

 pseudo-ova that I ever found at one time beneath a scale of this spe- 

 cies was twenty-four, of which number twenty-one or twenty-two were 

 fully developed young ones. This was in the month of May, and dur- 

 ing the same month I repeatedly found from eighteen to twenty of these 

 larvas beneath an adult scale. 



This species is very subject to the attacks of internal parasites, of 

 which no less than five different kinds are known to attack it in this 

 country alone. Of this number I have bred Encyrtus flavus Howard, 

 and Coccopliagus lecanii Fitch from specimens of this scale-insect col- 

 lected in this city. The Encyrtus attacks principally the larger scales, 

 each of which frequently contains three or four of the parasites lying 

 transversely to the longest diameter of the scale, and readily distin- 

 guishable by their lighter yellow color. On the other hand, the Cocco- 

 phagus principally attacks the younger scales, only one of the parasites 

 infesting a single scale, which it causes to swell up and assume a black- 

 ish color. I have frequently found whole colonies of these scales every 

 member of which had been destroyed by one or the other of these par- 

 asites. 



On the 11th of October, 1890, I collected several of these parasitized 

 scales, all of which had been killed by having been subjected to the 

 treatment with hydrocyanic- acid gas referred to in the chapter on the 

 Red Scale, and three days later an apparently healthy specimen of Coc- 

 copliagus lecanii issued from one of them. This parasite being in the 



