2372 Insects. 



have been previously observed ; or if so, T am not aware of the fact having been pub- 

 lished. These bees, it will be seen, are double-brooded, — a fact which I think is pe- 

 culiar to Halictus and Sphecodes. Truly " we are as yet scarcely upon the threshold 

 of the great temple." The experience of every ensuing season proves to me the truth 

 of this observation : compared with our knowledge of individual species, how limited 

 our knowledge of their economy in all its ramifications ! Even the history of those 

 which are daily before us, how incomplete ! 



It will thus be seen that, independent of structural differences, these bees are dis- 

 tinctly separated from the rest of the Andrenidas. The males of those bees forming 

 the genus Andrena disappear some time before their partners have completed their la- 

 bours, — the reverse of which obtains in the Halicti. On the 9th of October I met 

 with males of H. abdominalis, as well as of H. morio ; but not a female could I find, 

 although a month earlier they were plentiful upon the flowers on the same bank, at 

 which time the males also were in great profusion. 



Great numbers of the male Halicti I observed were preyed upon by the earwig 

 {Forficula) : I found remains of their bodies and wings, at the roots of a species of 

 Leontodon, in quantities : I therefore conjecture, that during the night, when numbers 

 of these bees are enclosed by the petals of flowers, the earwig ascends the plant and 

 devours them. Forficula I have observed to be a most destructive insect to bees, both 

 in the early and perfect stages of their existence, — whole colonies of Osmia bicornis, 

 Colletes and Anthophora being sometimes almost annihilated by them : it is a matter 

 of no consequence to them in what stage of progress the bees may chance to be ; they 

 devour pollen, pupa or imago, indifferently. Osmia and Anthophora, I have also this 

 year discovered, are subject to the attacks of small Chalciditous insects : as many as 

 thirteen larva were in one cell of Osmia, and about the same number in that of An- 

 thophora. Both these parasites belong to the genus Monodontomerus, each being a 

 distinct species : that found in the cells of Anthophora is about to be described by 

 Mr. Newport, he having bred it about the same time as myself, — the species not being 

 previously known. 



It will perhaps be said, that the fact of Sphecodes, as well as Halictus, being 

 double-brooded, is in favour of the opinion of the former being parasitic : such I freely 

 admit to be the case, and also that my observations are not conclusive. The indivi- 

 duals of the genus Nomada which are parasitic may be seen entering the burrows of 

 Andrenidae constantly and frequently : one species I have bred from the cocoons of 

 Eucera : here there is no difficulty, but having so repeatedly met with Sphecodes in 

 community with Halictus, and also with Andrena, and having so carefully watched 

 their operations, I cannot but think I must have observed them entering the burrows 

 of one of the genera ; but by the most careful observation I could never detect them 

 so doing. I would also observe, that the fact of my observing Sphecodes gibbus in 

 community with Andrena argentipes speaks in favour of their non-parasitism ; for it 

 must be obvious, that the eggs for the autumnal brood must be deposited in the nidus 

 of an Halictus or of an autumnal species of Andrena ; and I must admit that I can- 

 not reconcile to my mind the idea of a parasitic bee being parasitic upon two distinct 

 species, or first upon an individual of the genus Halictus, and then upon one of that 

 of Andrena ; still such an occurrence is possible, and it would be exceedingly inte- 

 resting to determine the question. 



A record of all observations made upon these genera will probably some day settle 



