213 



Scales from Tahiti. 



The inclosed samples were taken from trees recently brought in from Tahiti. The 

 large ones resemble the color of the bark, adhere very firmly, and are like Lecanium 

 olew in resisting dislTifectauts, even hydrocyanic .icid gas. These samples have all been 

 subjected to the ga« treatment and appear to be dead excepting the large round 

 species which we are unable to name satisfactorily. On the fruit you will find two 

 other varieties which do not appear on the tree except occasionally on foliage. * 

 • * [W. E. Collins, California, July 2, 1891. 



Reply. — Three different scales were found upon the samples of twigs and fruit 

 which were received recently from Tahiti. The large round species is Chionaspis 

 biclavia Comstock, described originally from specimens found upon several imported 

 plants in the greenhouse at the Department. It has never been found elsewhere 

 before receipt of this specimen from you and its original habitat has always been in 

 doubt for the reason that in our greenhouses it infests trees from several different 

 localities. The narrow scale on both twigs and fruit belongs to the species known 

 in p-lorida as the Purple Scale (Mytilaspis citricola), a form which is now almost cos- 

 mopolitan in its distribution. The round scale on the fruit is the common Red Scale 

 (Aspidiotus aurantii). All these scales were dead on receipt except the Chionaspis. 

 —[July 10, 1891.] 



Plant-louse on Celery. 



I send a sprig of celery from a garden near my office having upon it specimens of 

 an Aphis which our hop-growers claim to be identical with the genuine Hop-louse. 

 The patch of celery from which this was taken was nearly ruined by this louse last 

 season, the insect working upon it from early in the autumn. WTiether or not this 

 is the Hop-louse, it is certain that the genuine hop i)est has been seen from time to 

 time all winter upon the old Aines and rubbish in some of the gardens, and our 

 farmers say from the willows along the river l>anks. * * * [^■\Y, w. Corbett, 

 Washington, March 4, 1891. 



Rkply. — The insect is not the Hop-louse, but seems to be Aphis pasiinaei, the 

 common Parsnip Plant-louse. They were all dried or badly damaged, so that it is 

 impossible to accurately determine them. * * * The supposed Hop-louse which 

 you mention as having been seen on willows along the river bank is undoubtedly a 

 distinct insect. The Hop-louse has been studied for years, and is not known to go 

 from the hop plant to plants of other than the genus Prunus. Your informants are 

 also probably in error about the wintering of the Hop-louse on the old A-ines. * * * 

 [March 16, 1891.] 



The Rose Diaspis. 



I mail you today box of cuttings from a rose bush badly affected by scale insects, 

 which may possibly be the Icerya described in Insect Life for November, 1890, page 

 93. I first noticed it on a fine climbing rose which covered the side of my house at 

 Fern Bank, Ohio. This was in the spring of 1889. It spread rapidly, and by last 

 season covered the bush completely, although the shoots reached to the eaves of the 

 house, and last summer the bush died down completely and all the shoots were cut 

 off and burned. The root, however, still lived and threw up new shoots, but I see 

 the scale has begun to appear on them also. What treatment can you suggest for 

 the case?— [Edwin A. Hill, Ohio, January 5, 1891. 



Reply. — The insect is not the Icerya roscp, as you suggest, but the common Rose 

 Scale of this country and Europe — Diaspis ros(p. You will find this insect figured 

 and described in the Annual Report of this Department for 1880 (pp. 312-313 Plate 

 6, Fig. i). Your best remedy will be to spray your bushes thoroughly with a dilute 

 kerosene-soap emtilsion, made according to the formula given in Circular No, 1 of 

 this Division, — [January 3, 1891.] 



