In the larvæ of weevils (Calandra sommeri) there is a crop (Fig. 305), but not in the larva of Calosoma; also, according to Beauregard, in the pollen-eating beetles Zonitis, Sitaris, and Malabris it is wanting, while in Meloe it is highly developed (Kolbe).

The crop forms a lateral dilatation of the end of the œsophagus in the larvæ of weevils and of saw-flies (Athalia centifoliæ, Fig. 306).

The “sucking stomach” or food-reservoir.—This is a thin muscular pouch connected by a slender neck with the end of the œsophagus 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 (Ephemeridæ); in Platyptera (Perlidæ and Termitidæ), in Trichoptera, and in Mecoptera (Panorpidæ). In most adult Neuroptera (Myrmeleonidæ, Hemerobiidæ, and Sialidæ), but not in Rhaphidiidæ, the long œsophagus 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 larvæ of the Muscidæ, but according to Dufour it is wanting in some Asilidæ and in Diptera pupipara, and according to Brauer in the Œstridæ. The food-reservoir in Diptera is always situated on the left side of the digestive canal; there is usually a 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 reception 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 œsophagus, and has been seen in the bee to be filled with honey.

In the mole-cricket the hinder part of the crop is armed within with hook-like bristles directed backwards so as not to prevent the energetic pressure of the food backwards into the proventriculus, and to obviate the possibility of a regurgitation. (Eberli.)

The fore-stomach or proventriculus.—This is especially well developed in the Dermaptera, in the Orthopterous families Locustidæ, Gryllidæ, and Mantidæ, while in the Thysanura (Lepisma) there is a spherical gizzard provided with six teeth. It also occurs in many wood-boring insects, and in most carnivorous insects, notably the Carabidæ, Dyticidæ, Scolytidæ, in the Mecoptera (scorpion-flies), in the fleas, and in many kinds of ants, as well as Cynips, Leucospis, and Xyphidria. It is very muscular, lined within with chitin, which is usually provided with numerous teeth arising from the folds. These folds begin in the œsophagus or crop, and suddenly end where the mesenteron (“chylific stomach”) begins. It has been compared with the gizzard of birds, and is usually called by German authors the chewing or masticating stomach. (Kaumagen.)

The proventriculus is best developed in the Gryllidæ (Acrida viridissima), where the six folds at the end of the crop close together to form a valve between the crop and proventriculus. “They are each armed with five very minute hooked teeth; and, continued into the gizzard, develop many more in their course through that organ. These first teeth are arranged around the entrance to the gizzard, and seem designed to retain the insufficiently comminuted food and to pass it on to that organ.