214 FOREST ENTOMOLOGY. 



relatively small and of a peculiar form : this stage of development is 

 known in Coccid study as the period of fecundation. After the act 

 of impregnation the female changes her form, as represented in fig. 6. 

 This change in form is due to the hody being filled with eggs, and 

 up to the time when the eggs are deposited this stage is termed the 

 period of gestation. 



Thus, in a female Diaspid scale we have several stages viz., the 

 egg, larva (first and second moult), period of fecundation, and period 

 of gestation ; and in the male we have egg, larva (one moult), pupa, 

 and winged stage. 



Genus Mytilaspis. 



This genus, of which we have here only one species to consider, 

 may be distinguished from Chionaspis by the mussel-shaped scale of 

 the female. The scale is highly rounded, of a uniform light-brown 

 colour, and the second larval moult is completely covered by secretion. 



Male puparium rare, elongate, sides parallel, and there is a faint 

 hinge-like depression towards the middle. It somewhat resembles 

 the second stage female. 



Mytilaspis pomorum (Bouche). 



This scale - insect is unfortunately only too well known as a 

 garden pest. It infests apple, pear, and plum amongst our fruit-trees, 

 and hawthorn, mountain ash, cotoneaster, and wild -rose amongst 

 our forest trees and shrubs. Its common name " mussel-scale " is a 

 very appropriate one, inasmuch as it resembles, when magnified, our 

 common mussel of the sea-shore. The scale differs from that of Chion- 

 aspis in being more elongate, less circular, of a brown colour, and 

 about an eighth of an inch in length. It is built up in the same 

 manner as the ash-bark scale, but the first larval moult is yellow. 

 Plant after plant may be found so thickly covered. by the female 

 scales as not to be able to get a pin-point down without touching them 

 (not only covered with, but killed by, the scales), and yet not a single 

 male scale is to be found. Hence the species was almost considered 

 as parthenogenetic, and Mr Maskell says, "Male unknown in New 

 Zealand and Europe, doubtful in America." It was not until July 

 1896, after nine years of observation, that Newstead discovered the 

 male on broom at Bearstead in Kent. As the male had hitherto been 

 unknown, this was rather an important find. It may even now be 



