OF CERTAIN CHALCIDIDJE AND ICHNEUMON IBM. 67 



MONODONTOMERTJS NITIDUS. 



On the 12th of September, 1847, I detected, in several cells of Anthophora retusa, in a 

 dry clay-bank at Gravesend, a number of white Hymenopterous larva?, which at first I 

 mistook for those just described. There were from twelve to twenty-five in each cell, appa- 

 rently full-grown, and measuring each about one quarter of an inch in length. The body, 

 in these larvae (fig. 7 & 8), was formed of fourteen distinct segments, each divided trans- 

 versely on the dorsal surface into two, and covered with exceedingly fine, scattered, brown- 

 ish hairs. The head was small, and provided, as in all parasitic Hymenoptera, with short, 

 transverse, corneous mandibles, and the larvae had considerable power of locomotion, by 

 the extension and shortening of the segments. The whole of the food that had been pro- 

 vided for the bee-larva was already consumed, and the bee-cell contained only the para- 

 sites and the dried tegument and head of the young bee, which seemed to have been 

 starved. It was a question with me whether the bee-larva had not been killed by the 

 other larvae piercing it, and abstracting its fluids from without ? This query, then, 

 seemed to be answered by the circumstance that the number of the parasites was dis- 

 proportioned to the size of the victim, which, had it served as food for them, would in all 

 probability have been entirely consumed. Besides which, one anatomical fact showed that 

 they were external feeders, — their bodies were covered with a few scattered hairs, appre- 

 ciators of contact ; a condition which I have never yet observed in the soft-bodied, inter- 

 nal-feeding larvae of other Hymenoptera, and one which is as little required by them, as it 

 doubtless would be inconvenient. Added to this, the great power of locomotion pos- 

 sessed by these larvae, — which is neither possessed nor required by internal feeders, which 

 remain almost constantly in the same spot, — suggested the opinion that it is on the food of 

 the bee that these larvae subsist, and not on the young bee itself, which may perish merely 

 by deprivation of its proper nourishment. The larvae also exhibited some indications of the 

 formation of an anal outlet to the alimentary canal, which are not apparent in internal 

 feeders at this stage of growth. 



I preserved these larvae, in the cells in which they were found, through the following 

 winter, and although the remains of the bee were left with them in the cell, it continued 

 untouched, and they exhibited no further change until the middle of May 1848. At that 

 time some of the specimens gave signs of approaching transformation, in the shortened 

 and more shrivelled appearance of their bodies. Each of the larvae then spun some very 

 delicate silk, in small quantity. Shortly before they were ready to enter the nymph state, 

 the alimentary organs became perforated, and faeces were then passed for the first time 

 during the whole period of the insect's previous existence. The faeces passed were little 

 solid brown masses, that closely resembled the faecal masses passed by the pollinivorous 

 larva of Anthophora, which, like its parasites, as I have constantly found, passes nothing 

 from its alimentary canal until it is about to change to a nymph. These faecal masses 

 seemed to indicate the supposed nature of the food, — pollen and honey ; and to support 

 the opinion formed of the habits of these larvae from some points in their external anatomy. 

 From twelve to twenty masses were passed by each larva : these were composed of the 

 refuse of digestion and of epithelial cells accumulated during the period of feeding, and 



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