No. 6. DEPARTMENT OF AGRICULTURE. 239 



lowing spring. And !jo tlie young that are born after frosty days 

 and nights are fairly established, die before they reach a stage that 

 enables them to live through the winter. A badly infested tree ex- 

 amined in mid-\vi«ter will show many white and gray scales — all 

 dead; and plenty of fully developed females, some with young be- 

 neath their scales — also dead. The linng individuals are those 

 under the black scales, that may be considered half grown. These 

 become completely dormant and do not resume growth until the fol- 

 lowing May. The males appear about the middle of that month, ful- 

 ly three weeks before the females begin to reproduce; but after re- 

 production once begins there is little cessation iimil the end of the 

 season. 



The important points in this history are, that the insect passes the 

 winter well protected by a dense waxy scale, impenetrable to or- 

 dinary insecticides; that the newly born larvae are naked and un- 

 protected, readily reached by any contact poison; and that after raid- 

 summer, reproduction is practically continuous. 



PLANTS SUBJECT TO INFESTATION. 



In a general way all the ordinary orchard trees in the Eastern 

 United States are subject to infestation; but cherry suffers least — 

 some varieties being totally exempt. Quince suffers little and has 

 not been seriously damaged in any case that has come under my 

 notice. Peach suft'ers most and there seem to be no exempt varieties. 

 On peach the scale will ordinarily, if unchecked, kill trees the third 

 year from the date of infestation. Plums are almost as susceptible, 

 but individual varieties or even individual trees resist strongly, and 

 may live for several years, completely incrusted by the insect. 

 Apples are all good subjects, but the Ben Davis seems to be most sus- 

 ceptible and most difficult to clean. Pears differ widely and, where 

 mixed with other trees, Keift'ers are almost exempt. Most of the 

 Asiatic varieties suffer little, and individual trees may be entirely 

 exempt. Almost all the shrubby small fruits are subject to infesta- 

 tion; of these the currant is most injured, gooseberry the least. 

 Blackberry and raspberry are somewhat infested, but not ordinarily 

 much hurt. 



Grapes are quite generally infested, but are not harmed. The 

 slivery character of the bark on the old stock discourages setting by 

 the larva and the new growth is almost always cut off nearly to the 

 base; therefore the insects get little real opportunity. 



