Insects. 1801 



that its final change is completed within the bee's cell, and that it 

 emerges from this a perfectly developed beetle. 



Symbius Blattarum. The larva very closely resembles that of 

 Sitaris in figure; but has no anal appendages or setae. I cannot 

 make out whether it undergoes a foetal metamorphosis. It inhabits 

 the body of the cockroach {Blatta), and feeds upon the interior. 

 The female retains the larva form, never assuming the appearance of 

 a beetle. 



Horia maculata. The full-grown larva is obese, fleshy, and nearly 

 apod : it has indeed six legs, but these are very short and small : it 

 feeds in the cell of a wood-boring bee, and there undergoes its meta- 

 morphosis. As in the preceding instance, it has not been as- 

 certained whether the larva of Horia feeds on the bee-larva or on its 

 food. 



Apalus bimacalatus. The foetal larva is excessively minute, 

 active, and in structure resembles that of Meloe, which I shall next 

 describe. It has not been traced beyond this foetal state, there is no 

 doubt that it becomes parasitic, although its history is at present un- 

 known. 



Meloe Proscarabceus. The foetal larva of this insect has long been 

 well known to entomologists, but for some reason its true nature has 

 been doubted by two entomologists of great eminence, Dufour and 

 Kirby, both of whom regard it an ametabolous parasite, the former 

 describing it as a Triungulus, the latter as a Pediculus. Very many 

 years have now elapsed since I solved this matter to my complete sa- 

 tisfaction : I could not believe the statement so confidently made by 

 De Geer, although at that very time repeated by a friend from actual 

 observation, that the very minute active parasites of wild bees were 

 the larvae of that ponderous beetle Meloe : why did they grow no 

 bigger ? what could they feed on ? I procured the females of 

 Meloe; I confined them with abundance of food, and a supply 

 of light and damp earth ; and I had the satisfaction to see that they 

 burrowed in the earth; formed a kind of cell or receptacle, ap- 

 parently by kneading the earth ; filled the receptacle with a pro- 

 digious mass of minute yellow eggs ; and again returned to the sur- 

 face of the earth to devour leaves and grass as before. I watched 

 these eggs day by day, and at last 1 had the satisfaction to see them 

 produce minute active little larvae, with six longish curved prehensile 

 legs, and two long caudal setae ; in fact, they were the Triungulus 

 Andrenatarum of Dufour, and the Pediculus Melittae of Kirby. This 

 hatching took place in the autumn or late in the summer, and on the 



