MEANS OF DISTRIBUTION". 57 
The local spread of the insect from orchard to orchard and from 
tree to tree must also be brought about thru the agenc} T of means 
other than those under the control of the insect itself. The female is 
wingless and after once becoming fixt can not move. The young lice, 
as before stated, are active, crawl rapidly, and may reach other trees, 
but this is rare unless the limbs interlace, since we have shown by 
breeding-cage experiments that the larvae normally crawl but a few 
inches. Such spread, however, is comparatively insignificant except 
in the case of nursery stock, which is grown close together. It is 
possible that strong winds may carry the young bodily from one tree 
to another, or the}^ may be floated on water to distant points, particu- 
larly in irrigated districts, but the principal method of the spread of 
these young lice is by means of other insects and by birds. The active 
young lice soon crawl upon any small winged insect, particularly if 
the latter be of a dark color, and may thus be carried considerable 
distances. They are frequently found crawling upon ants, which are 
great travelers. It is extremely probable that they also crawl upon 
the feet of birds, and ma}^ be transported by these carriers for many 
miles. 
Some interesting observations have been made by Mr. Schwarz upon 
the transporting of these scale larvae by other insects. A little black 
ladybird, Microweisea {Pentilia) misella Lee, which was very active 
in devouring scale larvae, was unfortunately equalty efficient in trans- 
porting many of these young lice to other parts of the tree or to other 
trees; in fact, it was difficult to find a single beetle which did not carry 
on its back at least one larva of the San Jose scale, and sometimes three 
or four were found upon a single wing cover of a beetle. The small 
black ant, Monomorium minutum Mayr, was particularly abundant 
upon pears, attracted by the juices emerging from cracks, and almost 
every one of these insects carried on its back one or more specimens 
of the young scale insects. Specimens of the little chrysomelid beetle 
Typophorus canellus Fab. were also found upon the trees. Both red 
and black specimens of this beetle occurred, and the interesting obser- 
vation was made that while Aspidiotus larvae crawled freely on the 
black individuals, no specimens were to be found upon the red ones. 
The same peculiarity was found to hold true with the ants. The red 
ant, Formica schaufussi Ma} T r, was abundant upon the pears, but no 
specimens were found bearing Aspidiotus larvae, while, as just stated, 
the little black Monomorium was always found carrying them. 
As illustrating this transportation of the scale by birds or insects 
the experience at Riverside, Md. (Bui. 3, p. 25), may be cited, and 
Professor Smith reports a similar instance in New Jerse}^, in letter of 
January 13, 1896. 
In spite of the abundance of insects which may transport the larvae 
the progress of the scale from infested trees to noninfested trees is 
