14 The Bulletin. 



March to June, depending on season, altitude, climate, etc. After 

 crawling for a short time the young insects insert their beaks (suck- 

 ing-tubes) and begin to feed. Then the scale begins to form over 

 the body, and the insect is thus confined at that spot. AVhen the skin 

 is shed, the legs, eyes, and antennae (feelers) are shed off with it, and 

 thereafter the female insect is always eyeless, legless, and wingless; 

 simply has the organs for taking and digesting food and for repro- 

 duction (Fig. 5). It takes the female from thirty to forty days to 

 reach maturity and the males not quite so long. The male develops 

 finally into a tiny, yellowish, two- winged flying insect (Fig. 6)^. 

 The mature insect has no mouth for taking food, but is provided with 

 an extra pair of eyes ; this renders it more proficient in finding mates, 

 and thus aids in the multiplication of the species. In this State 

 there are jjrobably from five to eight generations in a season, and as 

 a single female may bring forth many sets (broods or litters) of 

 young, progeny of a single fertile female, in the course of a season, 

 if there were no fatalities, would by actual calculation number among 

 the billions. Kemembering tloat many of the insects are destroyed by 

 enemies or weather, as described later, we can still see that it is no 

 wonder that a tree that becomes infested while young is almost sure 

 to die unless thoroughly and persistently treated. The most active 

 period of increase is during August, September, and early October. 

 Breeding ceases when really cold weather sets in, usually between 

 the middle of I^ovember and middle of December, though in mild 

 winters the insects have been known to breed in the warmer parts of 

 this State in January. During the winter the adult insects nearly all 

 die, so that it is mostly the partly-grown insects that pass the winter. 

 These overwintering scales are small and are very dark in color. 



The San Jose Scale does not devour the leaves or fruit of a tree as 

 do some kinds of destructive caterpillars. Its method of obtaining 

 food is to insert the tinv beak into the tender inner bark and suck out 

 the sap. Hence a tree which is badly attacked is weakened by loss 

 of its sap, and usually puts forth scanty foliage in the spring and 

 may be unable to mature a crop of fruit. 



HOW THE INSECT SPKE^VDS. 



We have seen that the insect can only crawl about for a few hours 

 after birth, and that therefore it could only spread very slowly, and 

 only during the breeding season, if it were entirely dependent upon 

 its own powers. As a matter of fact, however, there are various 

 outside agencies which aid them in spreading into new trees, new orch- 

 ards and new localities. Chief among these outside agencies are: (1) 

 Wind, (2) Birds, (3) Insects, (4) Commerce in nursery stock. 

 These, with its own limited natural powers, constitute its principal 



