NOTES ON THE REPUGNATORIAL GLANDS OF 

 CERTAIN NOTODONTID CATERPILLARS. 



Glenn W. Herrick and John D. Detwiler. 



In the course of a study which the writers are making of the 

 life histories and habits of the red-humped apple caterpillar 

 {Schizura concinna) and the yellow-necked caterpillar {Datana 

 ministra), the junior author noted that while handling the 

 caterpillars of the former species, especially when they were 

 pinched with forceps, a considerable amount of moisture 

 would suddenly appear in an area about the body of the larva 

 as it lay in the hand or rested upon the table. Curiosity as to 

 the source of the moisture was aroused and the following 

 experiments were made by the writers to determine its origin, 

 nature, and method of dispersion. 



The presence of repugnatorial eversible glands in Notodontid 

 caterpillars has been known since the time of DeGeer, and 

 Packard* gives a list of nine species in which the glands have 

 been found. S. concifina appears in the list and Packard 

 remarks as follows concerning it. 



' ' While examining the very gaily colored and heavily spined 

 caterpillars of Schizura concinna, I observed that when a fully 

 grown one was roughly seized with the forceps or fingers it sent out 

 a shower of spray from each side of the prothoracic segment, 

 exactly like that oi Cerura and Macrurocampa.'' Several years 

 previously a note from C. S. Denhamf appeared in Insect Life' 

 in which he said that in rearing a brood of these caterpillars he 

 "discovered that they had the power to emit quite a quantity 

 of strong hydrochloric acid strong enough to be decidedly 

 corrosive to the skin and easily perceptible in the atmosphere. " 



In investigating the source and nature of the moisture which 

 appeared whenever the Schizura larvae were handled at all 

 roughly it soon became evident that these caterpillars possessed 

 considerable amounts of the liquid and that they were able to 

 eject it to a surprisingly long distance and over a comparatively 

 large area. In determining the habits and behavior of the 

 different individuals of Schizura concinna in ejecting the liquid 



* Jr. N. Y. Ent. Soc, Vol. Ill, pp. 110-127, 1895. 

 t Insect Life, Vol. I, p. 143, 1888. 



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