69 



smaller ones, finally killing the bark and eventually the tree itself. It was first no- 

 ticed on trees which were bought from a New York State nurseryman. If some 

 remedy is not soon applied it is feared the disease will spread throughout the Walla 

 Walla fruit belt. Will the Department kindly give me the cause and preventive of 

 the disease ? Can trees be saved which are in the first stages of the disease ? Please 

 communicate with me at your earliest convenience and the remedy, if any, will be 

 published in ^^ The Washington Farmer^' for the benefit of the fruit growers of the 

 Walla Walla Valley and entire northwest. — [Wm. M. Freeman, Walla Walla, Wash- 

 ington, March 24, 1890, to Mr. Van Deman, Chief of Division of Pomology. 



Eeply.- Mr. Van Deman, the Pomologist of this Department, has referred your 

 letter of March 24, relating to the new apple and pear-tree pest, to this division for 

 reply. The specimen of bark taken from the trees in the orchard of J . M. Gose proved 

 to be infested with a scale insert known as Aspidiotus perniciosus. This scale has been 

 recorded as very injurious in California and Nevada. It is described and figured in 

 the Report of the Department of Agriculture for 1880, page 304. It is further dis- 

 cussed in the report for 1881-'82, pages 65 and 207. I think by careful application of 

 the following-described remedies you will be able to prevent further injury by-it. The 

 best means against scale-insects, as shown by long experience in the work of the 

 division, is the emulsion of kerosene and soap, a formula for the preparation of which 

 is inclosed on separate sheet. In California experiments have been made by agents 

 of the Division which show that resin formula (see Insect Life, Vol. ii, No. 4, Oct., 

 1889, p. 92) may be used with the best of results against scale pests and Aphides. 



Numerous experiments have been made with one part of the compound to 8 parts 

 water, and this strength for most purposes will be sufficient. Both the resin wash 

 and the kerosene emulsion should be applied by means of a force pump and spray 

 nozzle. Any good nozzle that will cause the liquid to break into a fine mist-like spray 

 will answer the purpose. 



The bug inclosed with the bark is the Twice-Stabbed Lady-bird (Chilocorus bivul- 

 nerus), a well-known enemy of many injurious insects, including scale insects and 

 Aphides, and it was doubtless engaged in devouring the scales on your trees. — [April 

 1, 1890.] 



The Sow Bug. 



A small 14-Iegged crustacean (Oniscus) is very destructive to low growing flower- 

 ing plants in my garden and those of my neighbors. Would you please inform me if 

 you know of any way of getting rid of them outside of crushing them with hand or 

 foot ? Will send you specimens of the little pest if you so desire. It is especially 

 fond of flowers of violets and hearts's-ease or pansies. — [G. Kohu, New Orleans, La., 

 April 19, 1890. 



Reply. — We shall be glad to receive specimens of the Oniscus of which you com- 

 plain, and beg to ask you if you are perfectly sure that this is the creature which is 

 damaging your flowers and plants. In other words, have you seen it at work? A 

 full account of its damage will be acceptable to us and we shall be glad to publish a 

 note on the subject if you will favor us with the result of your observations. They 

 are popularly supposed to feed mainly if not entirely upon decaying vegetation. Do 

 you find that they feed at night or not ? With a little more information from you 

 we may be able to suggest a remedy. — [April 22, 1890. 



Traps for the Winter Moth again. 



There is one point in reply to which, if you are quite willing, I should much like to 

 be allowed to insert a few lines. 



It is to the paragraph headed "Traps for the Winter Moth Useless," p. 289 of March 

 number of "Insect Life" for 1890. Mr. R. McLachlan is mentioned as having 

 stated that traps which aim at destruction of the males of the Cheimatobia bnimata are 

 useless, as enough will remain to fertilize the winged females. This I should have con- 



