818 THE entomologist's record. 



approximaria on birch, and is not so velvety. Apprnximaria, as far as 

 I can gather, is dihitata, fore-wings no object, but hind-wings are 

 very narrow, and margin runs across the wing, and not parallel with 

 the cilia. In diliitata this starts, in well set specimens, not from the 

 anal angle of the hind-wings, but above, and runs at the same dis- 

 tance from the cilia all the way along the wing. In approximaria it 

 starts from anal angle and runs across the wing, more like filiiiram- 

 maria.'' Mr. Pierce's bred specimen (unfortunately, without history) 

 seems to mo to be a stunted and narrowed form of nehulata, and I 

 should have thought, from the evidence of Mr. Webb's cabinet, that 

 Mr. Gregson, in the olden times, w^ould have referred it to his prenir- 

 mria. It certainly does not belong to the filir/rawmaria group, and I 

 have a bred $ from Epping Forest entirely agreeing with it. The 

 captured specimen, named approximaria by Mr. Gregson, is certainly 

 a normal nehulata, with Avhich the genitalia perfectly agree, and could 

 be matched by dozens of Loudon specimens. 



I am afraid I have trespassed most unwarrantably on your 

 patience, and can only, in conclusion, reiterate the hope that I may 

 have succeeded in stimulating a fresh interest in this perplexing genus. 



On the habits of Metoecus paradoxus and Velleius dilatatus. 



By W. H. TUCK, M.A. 



Every autumn I am asked by many correspondents for specimens 

 of the wasp-beetle {Metoecus paradoxus), w^hich is very common in my 

 district, in favourable seasons. I am of opinion that if the nests of its 

 host, Vi'spa ruh/arif:, the small "anchor-faced" wasp, were more 

 frequently examined in the proper season, the parasite would be often 

 obtained. 



With me it occurs in about a fifth of the nests I open. I have 

 found 24, 12 and 8 in one nest, but 4 and 2 are the usual numbers, 

 and then generally in pairs. I have taken 17 of the beetles this 

 autumn, from seven nests, out of 24 examined — the first, August 2nd, 

 the last, October 1st, which gives a pretty wide margin for search. 



The life-history of this interesting beetle is still involved in much 

 mystery, and although I have taken a large number at different times, 

 I can ofter no explanation upon the following points, r/c, why the 

 perfect insect is seldom, if ever, found outside ; how the female passes 

 the time until she finds and enters the nest ; and how the race survives 

 when two or more wet seasons prove fatal to its host. 



As far as I can ascertain, the female beetle — which probably lives 

 underground — enters the nests from about the middle of July, and 

 remains in them until they are sufficiently advanced to lay her eggs ; 

 and no insect is more irregular than this wasp, as I have seen plenty 

 of nests from July to December. 



The eggs are very soon hatched, and the grub grows rapidly, and 

 having consumed a certain number of the wasp grubs, spins itself up 

 in a cell side by side with the young wasp grubs — generally the males. 

 The perfect insect appears to Avait for some time in its cell, possibly in 

 order that the wasps may liberate it by eating away the silken cap, 

 and it is not difficult, by the aid of a good glass, to find the parasite, 

 but in some cases the cap must be removed. When this is done, the 



