REPORT OF THE ENTOMOLOGIST AND BOTANIST. 209 
_ elongated shape. The legs and feelers have appeared again, and there are now promi- 
nent wing pads extending along the sides of the body. About twenty days after birth 
the male insect changes to the true pupa, in which all the parts shown in the pro-pupa 
are much more developed, and a slender organ at the end of the body called the style 
has appeared. From four to six days later, or from twenty-four to twenty-six days after 
birth, the males mature and emerge by backing out from the rear ends of their scales; this 
is chiefly by night or in the evening. 
The changes which have gone on beneath the female scale are less striking than 
those described above. After the first moult the body of the female is practically an 
= a almost circular, flattened sac, with 
indistinct segmentation and with- 
out any visible organs, except the 
long sucking bristle with which it 
draws up continuously the sap of 
the tree it is infesting. The female 
moults a second time about 20 
@ days after birth, and the last seg- 
ment now shows the important 
characters of the mature female, 
which are of so much service in 
the exact identification of the spe- 
cies. The segmentation of the 
body at this stage is quite distinct. 
a 
fl" ! Hiv 
i. 
Sree 
mi Ep Fone 
th aE 
: “t 
Thirty days from birth the 
females are full grown and the em- 
bryonic young may be seen within 
their bodies. The mature female, 
prior to the development of the 
young, is ,', of an inch wide by ;'; 
: of an inch long. The length of 
b.) Seal ae <a age) J a aa ; time necessary for the development 
() Seale puch cnlagsed, (g) Female showing yous, of a generation varies somewhat 
according to the Washington ob- 
servations, it covers a period of from 33 to 40 days from the time a young larva appears 
until it develops into a mature female bearing young. The San José Scale is enormously 
prolific. It has been calculated that a single female may be the progenitor of 3,216 
million descendants in a single season. 
The exact identification of the species is of the greatest importance, for the San 
José Scale is now known to have many very bad characteristics not possessed by several 
other scales which resembie it very closely in appearance ; and these make it a matter 
of public interest that no effort should be spared to control so dangerous a public enemy 
whenever it is detected in anew locality. The chief differences, in this connection, 
between the San José and some of these other scales are: (1) the fatal effects on the tree 
due to its greater rapidity of increase, and (2) certain minute but important structural 
characters which can be seen only with the help of a microscope. 
The careful experiments at Washington, already alluded to, show that in one 
season from a single female an increase of 3,216 millions is possible. It is not, of course 
to be expected that all of these would survive ; but with the San José Scale there are 
many circumstances which make it less liable to diminution than many other insects. 
As a matter of fact, it is known that this scale does not spread from a new point of 
infestation with very great rapidity to contiguous trees, and also that, when once estab- 
lished upon a tree, it soon increases enormously in numbers—indeed, unless checked, 
usually spreading rapidly over the whole tree and destroying it. This rapid increase is 
characteristic of the species and is due, of course, to the great fecundity of the females. 
The fact that they bring forth their young alive throughout the season and that these 
are very quickly protected by a scale which is impervious to many liquids, affects very 
8a—14 
