
No. 429] | THE MOUTH PARTS OF INSECTS. 695 
and effectively the whole study of the development of imagi- 
nal mouth parts in holometabolous insects to be overlooked 
because of the lack of any crying need for an ontogenic con- 
firmation of the hymenopterous homologies. Mr. Spaulding 
has been admirably successful in so clearing and staining the 
heads of variously aged larve of the honeybee and of a digger 
wasp, Ammophila s., that the developing imaginal head 
within the larval integument may be as easily studied as the 
exterior of the larval head itself. The bee and wasp larve, it 
will be recalled, are both “inside feeders,” z.e., lie during their 
life enclosed in a protecting cell, in one case of wax, in the 
other of hardened mud, and thus may and do dispense with the 
heavily chitinized opaque head cuticle common to exposed 
insect larvae. And both larva have full complements of mouth 
parts, namely, mandibles, maxilla, and labium, — a condition 
not common to all larvae in those two orders, Hymenoptera 
and Diptera, in which the post-embryonic 
metamorphosis is most radical. This con- 
dition is a necessary one for the determi- 
nation of the relations of the imaginal to 
the larval parts. 
Ammophila sp. (Figs. 13-15). — The 
larval mouth parts (Fig. 13) consist of 
well chitinized crushing mandibles (sd.), 
short fleshy maxillze (mr.) with very small 
one-segmented palpus (mr.p.) and smaller ^ afar o digger vam 
terminal lobe (mzx./.), and short liplike 4 — la sp. md., 
. ae MeL M s dame A, 
labium (Z) with pair of very small one- di: all bike’ med, 
segmented palpi (/L?.). The adult wasp ppap cer — 
also has a complete complement of mouth 
parts (Fig. r4), all very elongate and slender, the mandibles 
(md.) heavily chitinized and toothed, the maxille (mr.) long 
and slender with distinct cardo and stipes, five-segmented palpus 
(mx.p.), and simple terminal lobe composed of the fused galea 
and lacinia, and the labium (/7.) also long and narrow with fused 
submentum and mentum, four-segmented palpi (/7.f.), slender 
ligula formed of the fused glossz ( gl), and distinct slender para- 
glossae (p.¢.) less than half as long as the fused glossae. 

