THE FOOD-RESERVOIR 305 



The " sucking stomach " or food-reservoir. This is a thin muscular 

 pouch connected by a slender neck with the end of the oesophagus 

 or the crop, when the latter is present. There is no such organ in 

 Orthoptera, except in Gryllotalpa. It is wanting in the Odonata 

 and in the Plectoptera (Ephemeridae) ; in Platyptera (Perlidse and 

 Termitidse), in Trichoptera, and in Mecoptera (Panorpidae). In 

 most adult Neuroptera (Myrmeleonidae, Hemerobiidae, and Sialidae), 

 but not in Rhaphidiidae, the long oesophagus is dilated posteriorly 

 into a kind of pouch or crop, and besides there is often a long " food- 

 reservoir " arising on one of its sides, that of Myrmeleon (Fig. 307) 

 and Hemerobius being on the right side. 



A true food-reservoir is present in most Diptera (Fig. 308) as well 

 as in the larvae of the Muscidae, but according to Dufour it is want- 

 ing in some Asilidae and in Diptera pupipara, and according to 

 Brauer in the (Estridse. The food-reservoir in Diptera is always 

 situated on the left side of the digestive canal; there is usually a 



FIG 



rese: 



FIG. 308. Digestive canal of Sarcophaga carnaria: a, salivary gland ; b, wsophagus ; c, food 

 rvoir ; f-ff, stomach : h, intestine ; i. urinary tubes ; k, rectum. From Judeich and Nitsche. 



long neck or canal, while the reservoir is either oval or more usually 

 bilobed, and often each lobe is itself curiously lobed. 



In Lepidoptera (Figs. 309, 310) the so-called " sucking stomach " 

 is, as Graber has proved, simply a reservoir for the temporary recep- 

 tion of food; though generally found to contain nothing but air, 

 Newport has observed that in flies it is filled with food after feeding. 

 He has found this to be the case in the flesh fly, and in Eristalis he 

 has found it " partially filled with yellow pollen from the flowers of 

 the ragwort upon which the insect was captured," the pollen grains 

 also occurring in the canal leading to the bag, in the gullet, and in 

 the stomach itself. Graber has further proved by feeding flies with 

 a colored sweet fluid that this sac is only a food-receptacle. As he 

 says : " It can be seen filling itself fuller and fuller with the colored 

 fluid, the sac gradually distending until it occupies half the hind- 

 body." 



The food-reservoir of the Hymenoptera is a lateral pouch at the 

 end of the long, slender oesophagus, and has been seen in the bee to 

 be filled with honey. 



