UROCERID-E. SIREX. |15 



robust, silky, finely punctured and deep blue-black above and below; the 

 appendage at the apex short and conical ; ovipositor also blue-black ; 

 femora rusty-red, with a blue gloss at the base; tibiiB testaceous; tarsi a!so 

 testaceous, with the terminal joint fuscous; antennse black ; wings hyaline, 

 pale testaceous, with the limb dusky, the nervures, costa, and stigma ferru- 

 ginous, the last darkest. 



Male blue-black, with the margins of the 3rd segment, and the whole of the 

 4th, 5th, 6th, and 7th red ; the hinder tibiiB and tarsi dilated, compressed 

 and dark blue-black; the penultimate joint of the tarsi red. 



Both sexes vary in having the femora sometimes entirely red, at others more 

 or less clouded with blue-black ; the tibiae are occasionally clouded with the 

 same on the outer side ; the number of joints in the antenna appears to be 

 variable, and the blue colour is frequently enlivened by tints of brightish 

 green. 



Male varies with the 6 basal joints of the antennte bright red, the abdomen 

 rufous, with the 2 basal joints and a patch at the base of the 3rd blue-black, 

 the appendage only to the 9th also blue-black, legs as above. 



This sex also varies in having the antennse totally black, and the abdomen, 

 with the exception of the 2 basal segments, bright red : this has been called 

 Si. nigricornis of Fabricius, which is an American insect, and from which it 

 differs in several particulars. 

 This beautiful and extremely variable insect is decidedly the most 



common, at least in this country, of the genus ; it occurs near Birch 



B. Maxillary palpi m\\axi\cu\BX.e ; /aZ»za/ triarticulate. 



fSp. 5. Spectrum. Niger, litura ante alas utrinque testaced. (Long. corp. 

 1 unc. 1—2 lin. ; Exp. Alar. 1 unc. 6 lin.) 



Si. Spectrum. Linne.— Stewart {l)—Steph. Catal. 343. No. 4001, note. 



Head hirsute in front, glabrous behind, deep black, with a testaceous spot on 

 each side behind the eyes, which are brownish ; thorax black, with the 

 lateral margin crenulated and testaceous ; abdomen finely punctate-striate 

 transversely, its anal appendage rather long, acute, the base attenuated ; 

 ovipositor ferruginous ; legs pale lutescent, the femora slightly ferruginous 

 beneath ; the terminal joint of the tarsi dusky ; wings hyaline, with the 

 margins slightly clouded, anterior with a faint transverse fascia towards the 

 apex ; costa pale, stigma fuscous. 



Male with a triangular testaceous spot at the base of the mandibles ; femora 

 ferruginous, with the apex fuscous ; the 4 anterior tibise testaceous, with 

 the tip above fuscous ; the posterior glossy-black, with the base whitish ; 

 tarsi with the apex dusky. 



Stewart gives this as British, but I believe upon insufficient authority, arising 

 from the circumstance of Donovan having misapplied the name to Pimpla 

 instigator. 



h 2 



