THE CANAJU1A.N KNTOMOLOGIST. 87 



THE ODOUR OF COCCID^. 



BY PROF. W. G. JOHNSON, COLLEGE PARK, MD. 



I have been much interested in reading the notes upon the odour of 

 scale insects by Professors Webster and Cockerell in the January and 

 February issues of this journal. During my inspections in orchards and 

 nurseries I have frequently detected the odour emitte by Aspidiotus 

 perjiiciosus, mentioned by Webster, especially where the trees were badly 

 infested, and have wondered what relationship it bore to the species. I 

 have detected the most pronounced odours, however, in the genera 

 Chionaspis and Lecanium. The odour produced by the Euonymus 

 scale, Chionaspis etionymi, is very unpleasant to some persons. It is 

 most marked upon badly infested, freshly cut twigs. If they are left in a 

 tightly closed room for a {&vf hours, the air will become very foul. 

 When the scales are scraped or disturbed the odour is very offensive. 

 The foulest of all odours emitted by scale insects, with which I have any 

 knowledge, is that produced by Lecanium fiigrofasciatum, recently 

 described by Mr. Theo. Pergande (Bui. i8, Div. Ent. Dept. Agr.). It is 

 popularly called the peach Lecanium, but I prefer to call it the terrapin 

 scale on account of its close resemblance to that familiar animal. I am 

 not sure, however, but that the term stinking scale would not be more 

 appropriate, as it is certainly the most nauseating creature I have ever 

 smelt. During the past week I was able to determine, specifically, by 

 the scent with unerring accuracy specimens of this insect upon wild 

 goose plum enclosed in a pasteboard box, wrapped with paper, sent 

 through the mail for my examination, without opening the box. Two 

 years ago I saw a seven-year-old peach orchard in Worcester County 

 containing about 1,500 trees that was very badly attacked by this pest. 

 The orchard was examined in September, and the whole atmosphere at 

 that time was charged with this repulsive odour, which could be detected 

 many rods away. Two other cases came under my observation last fall 

 in the Blue Ridge Mountains, in Washington County One orchard, 

 eleven years old, containing about 900 peach trees, had become so com- 

 pletely overrun by this insect they were of no commercial value. The 

 most repugnant smell emanated from this orchard that I ever encountered. 

 The other orchard, peach also, contained 6oo six-year-old trees, all of 

 which were in the same general condition. When these insects are 

 crushed or rubbed with one's finger the odour is very sickening, and can 

 be detected on one's fingers even after repeated washings. 



Whether or not this odour is for the purpose of attracting the male I 



