27 



ning an open cocoon of coarse silk. In about a month the moths 

 emerge, and after mating - , lay their eggs. 



RELATIVE PROPORTION OF THE SEXES. 



My assistant, Mr. Kirkland, from whose observations I have taken 

 the more iinportaut facts in this paper, collected a large number of the 

 pupae in 1897, and the moths emerged as follows: 



Date. 



Males. 



Females. 



Date. 



Males. 



Females. 



Julv 7 



5 

 12 

 41 

 153 

 32 

 64 

 61 



2 



8 



38 



135 



46 



54 



100 



1 



July 14 



21 

 9 

 



1 



53 



8 



* 15 



12 



9 



16 







10 



17 



3 



11 



Total 





12 



399 



451 



13 









IRRITATION CAUSED BY THE HAIRS. 



While in the larval and pupal stages these insects are the source of 

 a great deal of annoyance from the intense irritation which is caused 

 by their hairs when they come in contact with the skin of a person, 

 especially when one is perspiring. Many persons in the infested region 

 suffered so severely as to require the aid of a physician. Some of the 

 gipsy-moth employ* es were so badly affected in the work of destroying 

 the caterpillars the present season that the chemist employed on the 

 work, Mr. F. J. Smith, was directed to investigate the matter, to ascer- 

 tain what was the real cause of the irritation, and to discover, if possi- 

 ble, an antidote. These investigations are not yet completed, but so 

 far as alieady carried seem to disprove the idea at first entertained that 

 it was caused by formic acid; nor can anything be extracted, as Mr. 

 Smith informs me, that will irritate the skin. 



Mr. Smith made extracts from molted caterpillar skins with water, 

 alcohol, ether, chloroform, and petroleum ether, a list of solveuts that 

 he thinks would dissolve anything in the nature of organic acids or 

 alkaloids if they were present. In the water extract the water becomes 

 slightly colored, but does not become charged with any nettling mat- 

 ter. The alcoholic extract removes a great many spines, which may be 

 seen floating on the surface of the liquid. Ether gives an extract a 

 little more pronounced than chloroform, both removing the spines in 

 large numbers. If the unfiltered extract be rubbed on the skin it pro- 

 duces the nettling sensation, while the filtered extract does not. From 

 these experiments Mr. Smith is inclined to think that the irritation 

 caused by the spines is mechanical and not due to chemical substances. 

 Further investigations, however, may lead to different conclusions. 



The nettling of the skin may be caused by contact with the caterpil- 

 lars, both old and young, or the cocoons, but in the latter case contact 

 is not necessary, as the hairs from the cocoons are blown about by the 



