DISPERSION OF GIPSY-MOTH LARV^ BY THE WIND. 3 



FORMER INVESTIGATIONS OF HAIRS ON SMALL LARVAE. 



The bodies of first-stage larvae (PI. I, fig. 1) are provided both 

 dorsally and laterally with two types of hairs, or setae, namely, short, 

 smooth hairs bearing a vesicle about the middle and very long, slender 

 ones which are covered with spinules. Wachtl and Komauth in 

 1893 first described the aerostatic setae found on the first-stage 

 larvae of P. dispar L. and Lymantria monacha L. and designated 

 the balloon-shaped swellings occurring on these setae as aerophores. 

 They suggest that these aerophores assist in the dissemination of the 

 young caterpillars through the air. 



Prof. Cholodkovsky in 1894 made some investigations and found 

 that the swellings or vesicles shrank hi dead larvae. His discovery 

 tended to weaken the theory that these swellings contain air and to 

 suggest that they may contain a fluid which will naturally dry up 

 after death. He also found that the swellings remained for months 

 in alcohol as full and rounded as in living larvae, and if the preparation 

 was allowed to dry on a slide the aerophores quickly shriveled. 

 He therefore concluded that they did not contain air but a fluid 

 which was probably poisonous and served as a protection against 

 insectivorous birds. 



Igenitzky, a student of Cholodkovsky, in 1897 further studied the 

 glands that give rise to the hairs and verified the findings of the former 

 investigator, who proposed to call the swellings " toxophores. " He 

 further states that the role of rendering the larvae more buoyant may 

 better be ascribed to the long thin hairs which resemble the pappus 

 of some plant seeds. 



Prof. K. Escherich in 1912 published a resume of former investiga- 

 tions into the function of the hairs and cites later work by Wachtl and 

 Kornauth in 1907 in which they cling to their former theory of aero- 

 phores. The latter found that the vesicles did not contain liquid, as 

 no reaction was noted by immersion in litmus, rosolic acid, or phenol- 

 phthalein, indicating that they contained neither alkali nor acid. 

 They did not shrink in alcohol, glycerin, or acetic acid, or excite any 

 capillary action; hence the investigators concluded that nothing but 

 air could be contained in them. Prof. Escherich lays stress on the 

 air refraction noted in connection with these balloons when immersed 

 in glycerin and viewed under the microscope. 



T. 0. Shcherbakov in 1914 published observations on the gipsy 

 moth in which he deals at length with tho function of the hairs on the 

 first and second stage larvae, and parts of his paper have been trans- 

 lated by Mr. J. Kotinsky of tho Bureau of Entomology. Shcher- 

 bakov says that the iuToplioros are not filled with air or gas and that 

 their connection with the glandular rolls would indicate that these 

 resides are probably filled with a poisonous secretion. Their oxceod- 



