86 Report of State Board of Horticulture. 



during the summer months hundreds of these little pests may 

 be seen, even with the unaided eye, as they crawl about over 

 the bark or fruit of infested trees. 



Even before the young insect has attached itself to the 

 bark the secretion of the scale has begun. At first it consists 

 only of a fluffy white mass of fine, waxy threads, which for 

 the first day or so of its existence causes the young San Jose 

 scale to appear as a miinute, downy, white speck upon the 

 bark. As these filaments become more abundant they be- 

 come fused into a more and more compact scale and assume 

 a yellowish color. Later the young scale-insect molts several 

 times during its growth and the fully developed scale is 

 thus made up of fused wax filaments and the several m^olted 

 skins. 



Each female of the over-wintering generation is capable 

 under favorable conditions of producing approximately one 

 hundred young. In the course of but one month these reach 

 maturity and the females begin to produce another genera- 

 tion. There are thus produced some four or five generations 

 during the entire season. Under supposedly favorable con- 

 ditions single females of the later generations have been ob- 

 served to produce approximately six hundred young. Basing 

 their estimates upon breeding-cage observations, Dr. Howard 

 and Mr. Pergande have shown that it would be possible 

 under the most favorable conditions for the progeny of a 

 single female to reach the astonishing number of 3,216,080,- 

 400 individuals in a single season. Should each of these 

 scales reach the largest size, one-tenth of an inch, and were 

 they all placed side by side touching each other in all direc- 

 tions there would be enough of them to cover approximately 

 five acres of surface. It is almost needless to add that in the 

 intense struggle for existence of organism with organism and 

 with climatic conditions such an astonishing rate of multi- 

 plication is not even approximated under natural conditions. 

 Nevertheless, when one realizes the enormous rapidity with 

 which this pest multiplies it is no longer a surprise that 

 careless work in spraying fails to give satisfactory results. 

 A feAv females here and there upon very small portions of 

 the tree which have not been reached by the spray may dur~ 



