POSTEMBRYONIC CHANGES OF HYMENOPTERA 663 



3 



gl-, 



we may call them, of certain egg-parasites (Proctotrypidae). He 

 discovered the iiuaginal buds of the wings in the third larva of 

 Polynema (Fig. 185), but his observations, and those of Ayers, need 

 not detain us here, as they have little to do with the subject of the 

 normal metamorphosis of the Hymenoptera, and will be discussed 

 under the subject of Hypermetamorphosis. 



To Bugnion we owe the first detailed account of the internal 

 changes in the Hymenoptera, his observations being made on a 

 chalcid . parasite, Encyrtus fuscicollis, a parasite of Hyponomeuta. 

 The apodous larva (Fig. 618) moults but once, the next ecdysis 

 being at the time of pupation. It passes through a semipupal stage. 



Bugnion observed in the larva of Encyrtus three pairs of lower 

 thoracic or pedal imaginal buds, two pairs of upper or alary buds, a 

 pair of ocular or oculo-cephalic buds 

 destined to build up all the posterior 

 part of the head, a pair of antennal 

 buds, and three pairs of buds of the 

 genital armature (ovipositor). He also 

 detected the rudiments of the buccal 

 appendages under the form of six small 

 buds (Fig. 619), which do not invagi- 

 nate, and are not surrounded by a 

 semicircular pad. Also in the ab- 

 domen, behind each pair of stigmata, 

 there is a group of hypodermic cells 



(Fig. 617), Which, without doubt, COr- 



respond to the wing-buds, but are not 



differentiated into a central bud and w " 



its pad, and does not merit the name of imaginal bud. In fact, 



except the eye-buds, which are unlike the others, he only observed 



the imaginal buds of the legs, wings, and ovipositor. The antennal 



buds are, like those of the buccal appendages, without an annular 



zone. 



The pedal buds were detected in the middle of larval life. They 

 each form a central bud surrounded by a circular thickening. They 

 gradually elongate and become tongue-like and somewhat bent; soon 

 a linear opening or slit appears, forming the mouth of a cavity 

 which communicates with that of the body, allowing the passage 

 into them of the tracheae, muscles, and nerves, and afterwards of the 

 blood. Finally, the buds grow longer and slenderer, are bent several 

 times, and show traces of the articulations ; and soon under the 

 old larval skin, now beginning to rise in anticipation of the moulting, 



