THE STRUCTURE OF THE SILK GLANDS OF 

 APAX TELES GLOMERATUS L.^ 



ROBERT MATHESOX AND A. G. lU'CCLES. 



Apanfrlrs (jhmcmius is a hyraenopteroiis social j»araHU- ..f the 

 larvae of Finis rapac, the eommon eahhaue worm. The adult 

 females deposit at each oviposition from fifte(Mi to thirty-five vii^zs 

 in the young larvae of Pieris. The parasite- on hat. hiuii. feed tipon 

 the lymph and fatty tissue of their host and oiow very rapidly, 

 becoming full grown at about tlie end of the larval life of the 

 caterpillar. They then penetrate through the skin of th(Mr iiost 

 and, while emerging, spin their characteristic sulphur-yellow co- 

 coons. The silk glands, as seen in sections of the mature larvae, 

 are enormously developed. Althotigli the silk glands of lepidop- 

 terous and trichopterous larvae ha\e been the objects ot detailed 

 study by Helm, Gilson, and others, very little is known concerning 

 these glands in the Hymenoptera. As regards histological struc- 

 ture the only works of importance arc those of ( liolodkovsky, 

 his student Pikel, and Bor.Uts; an.l. excepting the latter who 

 gives a brief discussion of ihc-^v glan.i> in the acnh-ate Ilymenop- 



larvae of various Tenthre.linidae. Theref.>re at the suguv-^tion 

 of Professor Rilev we were led to invotigate more fully the >ilk 

 glands of Apanteles. 



The work was carried on in the Knto.nologi. al Laboratory of 

 Cornell Universitv. We wish to extend onr thank, to Profe»ors 

 Comstock. Riley" and :Mac( Hllivray, for their constant aid and 

 advice. 



Anatomical Disposition of the Silk Glands.— The silk glands 

 of Apanfdc.s qhmcrafus arise near the base of the lal>inm and 

 extend through the body cavity to the antepenultimate segment 

 of the abdomen. Li the abdominal region of marnre larvae they 

 consist of two pairs of thin-walled, tnuch convohite.l. cylindrical 

 tubes (PI. 1, fig. 3) which completely surround the alimentary 



