454 The Enemies of the Wheat Flff. 



larger and the tenth longer and more pointed : but it is very re- 

 markable that whilst the females occasionally swarm, so little is 

 known of the habits of the opposite sex that I have not yet been 

 able to meet with a specimen. The only one I ever saw was cap- 

 tured by Mr. Haliday on a rose-tree, and the above characters are 

 translated from Mr. F. Walker^s paper upon the Genus Platygas- 

 ter* This is such an extensive group that he has described 99 

 species which inhabit this country, and amongst them is one na- 

 med P. Tritici by Mr. Haliday, who found it on corn and willows 

 in England and Ireland, and from its specific name it is evident 

 that talented naturalist considered it to be connected with our 

 wbeatfields.-l- 



" The second species described by Mr. Kirby he has named Ich- 

 neumon iNSERENs; it is apparently a Platygaster ; Jbut as I 

 have not been able to find the specimen in his collection, I must 

 be satisfied in transcribing his account and copying" his figures* 

 He says, " Upon the Yth af June I o-bserved a very minute Ichneu- 

 mon exceedingly busy upon the ears of wheat, which, at first, I 

 took for Ichneumon Tipulce ; but upon a closer examination I 

 found it to be a species entirely distinct, as will appear when I 

 come to describe it. As soon as I was convinced of this, and ob- 

 served that it pierced the florets at a time whea no larvas had 

 made their appearance, I conjectured that it must lay its eggs in 

 the eggs of the Tljmlay "This insect is furnished with an acu- 

 leus three or four times its own length (fig. c), which is finer than 

 a hair and nearly as flexile; this is commonly concealed within 

 the abdomen, but when the animal is engaged in laying its Qgg^ 

 it is exserted ; one day it gave me a full opportunity of examining 

 this process. It inserts its aculeus between the valvules of the 

 corolla near the top of the floret ; its antennoe are then nearly 

 doubled and motionless, its thorax is elevated, and its head and 

 abdomen depressed ; the latter, when it withdraws the aculeus, is 

 moved frequently from side to side before it can extricate it. This 

 insect has allowed me to examine its operations under a lens for 

 six or seven minutes : upon opening the floret into which it had 



* Entomological Mag., vol. iii, p. 220. 



f Curtis's Brit. Eot., foL 309 •, and Guide, Genus 585, where 108 species 

 are recorded. 



X I have included it in the Genus hiostemma in the ' Guide', a Genus 

 which has been formed out of Platygaster; but whether I have been right 

 in its location, I am unable at present to determine for want of materials* 



