URTICATING PROPERTIES OF LEPIDOPTERA. 43 



after Karsten, Keller and others have so clearly proved the 

 presence of glands at the bases of the spines of these stinging 

 larvae." 



And very much more, all tending to prove what Mr. South 

 says he has only seen suggested by Mr. Swinton, viz., that under- 

 neath the warts, on the hinder segments, glands are situated 

 which secrete a poisonous fluid, which is forced in minute drops 

 through the spines. 



Coming to the insects we have lately had under consideration, 

 Mr. Dimmock goes on to say, " The structure of the evaginable 

 warts and their glands in Leucoma silicis will answer in a general 

 way for the similar warts of Orgijia and of the European Liparis. 

 The wart is protruded by pressure of the fluids within the body, 

 and retracted by muscles ; at or ne ar its centre open the ducts 

 of one or two glands which are situated beneath the warts. The 

 position and general structure of these glands, as well as their 

 motion when the larvae are disturbed, indicate that they are 

 defensive in function." 



Just one more slight extract, which appears to throw a little 

 light upon the mode in which the imago causes urtication : — 

 " Still another form of gland is that at the anterior end of 

 certain homhycid pupae, which breaks when the imago spi'ings the 

 chitinous pupal skin, and leaves its secretion, which has been 

 termed bombycic acid, on the head of the moth." 



I trust these few extracts will give a fresh impetus to the 

 investigations of those gentlemen who have the time and means 

 of successfully following up this inquiry. 



George Balding. 

 Kuby Street, Wisbech, January, 1H84. 



Through the courtesy of Mr. Geo. Dimmock I have been 

 favoured with a copy of the American publication ' Psyche,' vol. 

 iii, No. 101, 102, containing a valuable and interesting paper by 

 that gentleman — one of the editors — " on some glands which 

 open externally on insects," in which are some observations 

 showing that the urticating properties of certain lepidopterous 

 larvae are due to the glandular hairs, somewhat of the nature of 

 those of the stinging-nettle. 



For every efi^ect there is a cause, and the irritation produced 

 by some caterpillars is a fact which cannot be gainsaid. It 



