HOW MOTH-GREASE SPREADS. 



91 



trap was placed on the old Clonbrok Castle, about sixty feet from the 

 ground. — N. chaonia. Six insects in my moth-trap in May, placed in 

 position as above. 



Ci/matopJiora or. One specimen in 1892 ; date uncertain. 



Bn/ophila vmralis. One specimen taken flying near sugar, July 

 20th, 1891. 



Moma orion. Three specimens taken and some larv?e which I did 

 not succeed in rearing, 1 saw an imago, on a hemlock-flower, with 

 Mr. Kane, at Mote Park, Co. Koscommon, but failed to take it ; July 

 19th, 1893. 



Acromjcta leporina. Have taken several specimens ; all are but 

 slightly marked with black. Not common. — A. aceris. One specimen, 

 July, 1891. — A. megacephala. Two specimens, July, 1891 ; one larva 

 on poplar, 1893. 



HOW MOTH-GREASE SPREADS. 

 By H. Guakd Knaggs, M.D., F.L.S. 



In the ' Entomologist' for April last (xxvi. 110), Mr. Anderson 

 broached a subject which may, for one thing, have useful results 

 in teaching us to pin our insects on fixed rules. He remarks : — 

 " Now it seems to me that grease does not alwaj's emanate from 

 the abdomen, but at times exudes from the thorax, and spreads 

 from the silky hairs clothing the thorax — oftentimes a part of 

 exceeding beauty — and covers the wings, and then it is that 

 grease is indeed a nuisance. I may be displaying my anatomical 

 ignorance here, and it may be that it is impossible for grease to 

 exude from the thorax. All I can say is then that many insects, 

 inter alia, Demas coryli, appear to grease in the thorax before 

 any trace of it is seen in the bodies." On p. 149 in the same 

 volume the Eev. Joseph Greene, in reply to Mr. Anderson, says : — 

 "He (Mr. A.) then suggests that grease may emanate from the 

 thorax, and not from the abdomen. I have never heard or read 

 of this theory before, and I cannot think that there is the slightest 

 foundation for it." And then the matter dropped. 



Mr. Greene's theory, we know, is that " It (grease) first appears 

 in blotches on the abdomen, and, if neglected, extends to the 

 thorax, corroding the pins, unless black pins be used ; thence to 

 the wings, and finally to the paper." Now, so far as my own 

 experience goes, moth-grease may first become visible on the 

 thorax under certain conditions, while it can never pass direct 

 from the abdomen to the thorax under ordinary circumstances, 

 the metaphragm having no opening except for the passage of 

 intestines, vessels, &c., and being, moreover, of a tough, imper- 

 meable nature ; consequently the abdomen being the great reser- 

 voir of the grease, the order of outward and visible signs is 

 generally as follows : — The first appearance is on the abdomen 



