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TEXT-BOOK OF ENTOMOLOGY 





Orgyia, Empretia stimulea, Hyperchiria io, the larvae of the saturnians 

 (Fig. 217) and lasiocampids, etc. They rarely occur in insects of other 



orders, though the skin of Tele- 

 phorus is said by Leydig to bear 

 glandular hairs. 



Leydig states that in the stout bristles of 

 Saturnia there is, as in the integument of 

 the body, a homogeneous cuticula, under 

 which is the cellular matrix (hypodermis), 

 and the clear contents (hyaloplasma) are 

 secreted from the blood. The cell-structure 

 of the hairs consist, as in the cells of the 

 body, of spongioplasma and hyaloplasma. 

 Leydig has observed the droplets of the 

 secretion of the caterpillar of Saturnia 

 carpini oozing through distinctly observ- 

 able pores, and states that there are similar 

 openings in the hairs and scales. Dewitz 

 found easily observable openings at the end 

 of the hair of a large exotic weevil (Fig. 130) . 



The advanced nymph of Psylla is also 

 armed with clavate glandular hairs (Fig. 

 178). 



The tubercles are outgrowths of the body- 

 walls ; they are either smooth, warty, or 

 spiny, as in many caterpillars. While the 

 armature of insects is of little morphological 



sc--- 



Fio. 216. Section of a subdorsal tubercle 

 from a larva in stage I : fte, the setigenous 

 cells, one for each seta ; pglc, nuclei by which 

 the poison is secreted ; , seta ; p, poison in 

 middle of a broken spine ; out, cuticle ; s</. 

 tub, spinulated surface of the subdorsal 

 tubercle. 



Fio. 217. Armature of last four segments of Callosamia promelhed : a, a dorsal seta ; b, one 

 showing the poison (p) within. 



