BULLETIN NO. 32, MARCH, 1S95. 107 



value with us in the East. This has been particularly noticeable in a 

 series of experiments which I conducted during the years 1893 and 1894, 

 through Messrs. Marlatt, Coquillett and Pergande, and the results of 

 which are em])odied in a paper by the former, Insect Life, Vol. VII, 

 pages 115-126). Some of the reasons for these varying experiences are 

 not far to seek. As a State, California has many peculiarities, especially 

 this, the southern portion of the State. It is essentially the land of 

 scale-insects, and why ? In the East the majority of our most injurious 

 species produce but one generation annnally, and the periods of hatching- 

 and developing, and the stages in which hibernation takes place are pretty 

 definitely marked. Thus, for a period of about two weeks, generally in 

 the month of May, all the young will hatch from eggs that were hiber- 

 nated under the female scale. And by spraying the plants affected dur- 

 ing this comparatively brief period, when the young and tender insects 

 are so easily destroyed, the plants are, for the most part, easily protected* 



"The species which hatch out very irregularly and produce more than 

 one generation annually are the exception there. Here with you, on the . 

 contrary, all your most injurious species go on multiplying the year round,, 

 and there is scarcely any definite demarkation between the different broods,, 

 or the periods of hatching or the different stages of development. There 

 is hardly any absolute period of rest, properly speaking, to be compared 

 with the winter period of from four to nearly eight months in the East. 

 Thus the winter washes, more particularly, vary in their effect in the two 

 sections, as the scales in the East, being more thoroughly dormant, are 

 not so easily killed." 



It is evident, from the irregular and continuous production of the 

 young of the San Jose scale during the summer months that the summer 

 washes, useful if re])eated with sufficient frequency, can hardly be 

 depended upon to exterminate the insect or entirely rid the tree 

 affected with it. The necessity of their fre(iuent use makes them, 

 also, more expensive. Any treatment that will be effective by 

 one application is preferable, especially if this can be applied in the 

 dead of the year when other horticultural operations do not command 

 so much time. Hence our chief reliance must be on what are known 

 as winter washes, or on the gas treatment already described. 



The lime-salt-and-sulphur wash which is used with so much satis- 

 faction against this insect in California proved much less satisfactory in a 

 series of experiments which I had made during the winter 1893-1894 

 both on the Department grounds on other species of armored scales and 

 on my own place at Sunbury. Ilie experiments were made on American 



