212 The Ohio Journal of Science [Vol. XVIII, No. 6, 



intestine, which, however, is present at this stage. The 

 pharynx-esophagus is long, extending back to the hind thoracic 

 segment. It is very narrow with a small lumen for the greater 

 part of its length, but broadens out gradually at first, then 

 abruptly, into the mid-intestine. The latter occupies the 

 greater part of the body cavity and becomes greatly distended 

 at maturity, food being taken in much more rapidly than it 

 can be digested, so that the entire mid-intestine acts as a food 

 reservoir. 



A set of powerful muscles is attached to the dorsal part of 

 the pharynx-esophagus and a smaller set below it. These act 

 in such a way that their contraction forces this structure open, 

 thus forming a sucking organ. Aside from these the only other 

 striped muscles in the larva of note are those controlling the 

 mandibles. The cells of the pharynx-esophagus are small. 

 Those of the anterior fourth of the mid-intestine are large, 

 columnar, and digestive in function, in contrast to those of the 

 greater part, which are elongate and flattened. 



The salivary glands are very large, appearing as two sets of 

 long convoluted tubes, one on each side of the mid-intestine, 

 extending about three-fourths the way down it in the mature 

 larva. Each set is composed of two branches ending anteriorly 

 in a short lateral tube. These two lateral branches open into 

 a common duct which extends into the spinneret. They serve 

 primarily as silk glands in the spinning of the cocoon. The 

 cells composing the main duct are columnar, thus differing 

 distinctly from those of the rest of the glands. Undoubtedly 

 the true salivary function is principally confined to this section 

 of the glands. 



There is no caudal vesicle on the larva as observed for 

 Apanteles (Tower, 1916), and no malpighian tubes have been 

 observed in any of the stages. Whether the waste products 

 are absorbed and discharged upon pupation, or whether they 

 are thrown off into the host is not known. The ten pairs of 

 spiracles lead into short lateral tracheae which open into the 

 two longitudinal trunks, the tracheal system in the mature larva 

 being very similar to the general type found. As in the third 

 instar the nervous chain consists of eleven ganglia. 



