Spilocrypti4S.] BRITISH ICHNEUMONS. 273 



and the post-petiole longer than broad ; terebra one-third of the length 

 of the abdomen. Legs with hind femora red, apically black ; S with 

 anterior coxae and trochanters white, black -spotted and the hind ones 

 black, also with base of tibiae, sometimes an obsolete spot beneath the 

 hind trochanters and the hind tarsal band, white, its anterior tibiae and 

 femora fulvous ; of 9 with anterior tibiae and femora red and black-lined, 

 the hind coxae red and black-marked, and the base of the tibiae white. 

 Wings hyaline ; areolet pentagonal, broad above ; nervelet wanting, ner- 

 vellus intercepted far below its centre ; tegulae and radix white, former 

 in 9 black. Length, 9-10 mm. 



The ? may be known from that of .V. vti}:;rator by its more elongate 

 form, narrower basal segment, unclouded wings, etc. The cheeks are 

 sub-intumescent, epistoma prominent, clyj)eus very flat and on the same 

 plane as the face, with its apical fovea as in .V. incubilor, the antennae are 

 exactly filiform with the two basal flagellar joints of equal length, the 

 metanotum uniformly convex, petiolar area small, the scutellum flat and 

 apically narrowed and diffusely punctate, and the abdomen is more 

 rounded laterally than is that of S. iucubitor. The 9 has the basal seg- 

 ment somewhat narrow and slightly curved apically, the post-petiole not 

 twice broader than the petiole and as long as broad, with its apical angles 

 acute and the apical margin deeply emarginate laterally, without carinae or 

 sulci. The $ has the basal segment narrow, slightly explanate apically 

 with sub-prominent tubercles, its post-petiole scarcely longer than broad 

 with the sides curved, as in the female. 



Ratzeburg, whose C. incubitor appertains to this species, says it is extra- 

 ordinarily similar to S. migrator, though somewhat more slender, with the 

 metathorax only feebly rugose-punctate and nitidulous before the basal 

 transverse costa. 



This species is also extremely closely allied with S. incubitor, from which 

 it may be distinguished by the points enumerated under the latter, but its 

 exclusive parasitism upon Tentliredinidae is very noticeable. 



In January, 1898, I found four or five cocoons of Trichiosoma tibialis. 

 Leach, on whitethorn at Westerfield, near Ipswich, all of which contained 

 empty cocoons of C. df?ibicis. From a batch of the host's cocoons from 

 Sudbury, Suffolk, one crippled ,$ emerged at 11-30 p.m. on June 30th, 

 1899 ; a second before 9 a.m. the next morning, and three more at 3-10 

 in the afternoon ; a sixth ,^ emerged on the 3rd July, and a 

 seventh, with the only ? , on the 5th ; twelve more S 3 

 emerged before 4 p.m. on the 7th. Among eleven of the 

 host's cocoons, found at Ipswich on 23rd February, 1900, was 

 one containing fifteen or twenty old cocoons of the parasite, 

 together with the host larva's skin, but with no trace of its 

 pupa, pointing to the conclusion that they emerge from the 

 host's larva shortly after it has constructed its cocoon. Inside 

 each parasite's cocoon was the larva skin, forming a dark mass 

 at the extremity opposite to that through which it had emerged. 

 The parasite's cocoons are rather flimsy, dirty white, 8 mm. in 

 ^•^oxyaLJthl!*" length, nearly 3 mm. in breadth, and often interwoven ujKJn 

 each other. In one cocoon was a dead 9 with the petiole 

 bent back ujwn the metanotum and the a])iccs of all the femora contracted 

 on to the thorax, with their tibiae pressi-d closely to them. The parasite 

 had emerged through three distinct orifices in the Trichiosoma cocoon. 



T 



