4. AND REX A. 25 



We now come to the last supposed parasite on these bees ; it is 

 found on their bodies, and exactly resembles in form the larva of 

 Meloe, but is of a brown-black colour, and is full twice the size ; 

 they attach themselves to the hairy parts of the bees, as the meta- 

 thorax and the sides of the thorax beneath the wings. "What these 

 Pediculi really are, is at present involved in complete obscurity ; 

 Mr. Kirby regarded them as insects in their perfect condition, 

 naming them Pediculus melittce. I have frequently observed these 

 creatures in considerable numbers in the flowers of Ranunculus 

 acris, as many as twenty or more in a single flower, about the 

 month of April, and, I think, always before the usual time for 

 meeting with the larvae of Meloe. I have found them on various 

 species of bees, usually on those which are most pubescent, as 

 Andrena fulva, thoracica, and nigro-cenea, also commonly on Melecta 

 armata, Antliophora retusa and acervorum : this circumstance would 

 appear to confirm or indicate a connexion between the insects, and 

 from analogy we might readily conclude that this Pediculus must be 

 a parasite on some species of bee ; but we have nothing in support 

 of this supposition, and against it we have the following observa- 

 tions : — Mr. Newport has shown that it cannot be the larva of Meloe 

 cicatricosus, and, as well as myself, has proved that it cannot be that 

 of M. violaceus or of M. proscarabceus ; and since the other species of 

 Meloe, M. variegatus and M. rugosus, do not occur near London, it 

 appears certain that it cannot be the larva of any species of that 

 genus, unless it be discovered hereafter that the larva of Meloe not 

 only increases in size in its hexapod state, but that it also changes 

 from bright orange to black. 



Another circumstance which induces me to hesitate in adopting 

 an opinion of the Pedicidus being a larva at all, is the fact that on 

 opening some cells of Anihophora retusa, which I dug up on Hamp- 

 stead Heath, I found two living specimens of the hexapod in the 

 same cell as the perfect bee : it is certainly possible that they might 

 have subsisted on a portion of the food laid up by Anthojihora ; but 

 here was no change of condition, and how came they into the cell ? 

 I am inclined to think that they, being insects in their perfect con- 

 dition, came there exactly in the same way as we find Forficulce, 

 having forced an entrance, which I did not observe, and that they 

 were in quest of food, seeking what they might devour. 



In the determination of the species of the genus Andrena much 

 difficulty will be met with, the similarity of the males of many 

 species being so great that nothing short of a long and attentive 

 study of them, combined with out-of-door observations, will enable 

 the student to discover those niceties of distinction which are easily 

 detected by the practised observer ; these difficulties are considerably 

 enhanced by the changes in the colour of the pubescence to which 

 they are subject from exposure. The species of the first division, 

 which are usually more or less red, are very inconstant — specimens 

 of the same species from one locality being highly coloured, whilst 

 those from another have all a tendency to a sombre colouring ; those 

 species which have fulvous or yellow pubescence are much changed 



