21 S ON THE SPECIES OF PLATYGASTER. 



often red; the wings are iridescent and pubescent. They run 

 swiftly, with their antennae incessantly vibrating, and are found 

 on trees, but more often among grass in fields and woods, 

 during the summer and autumn. They destroy the minute 

 Diptera {Cecidomyice, &c.) that infest the corn, grasses, 

 and other plants. These, while in the grub state, reside 

 within the inmost recesses of the florets, and the Platygasier 

 would be unable to reach to them were not its abdomen often 

 very long and slender, and flexible towards the tip ; it has 

 also a very long hair-like ovipositor concealed within the 

 abdomen when not in action. 



In the fourth and fifth volumes of the Linnean Transactions 

 is a long and interesting account of Tipula (Cecidomyia) 

 Tritici, by Kirby, who also describes three minute species of 

 Hymenoptera, that he found on the ears of wheat. 



The first of these Ichneumon (Platygaster) Tipulce, lays its 

 eggs in the grubs of C. tritici. He did not clearly ascertain 

 the history of the second, but he suspected it to be parasitic on 

 the eggs of the same fly ; the third, Ichneumon {Macroglenes) 

 penetrans, belongs to the Chalcidites. 



In the first volume of the Entomological Magazine there 

 is an excellent methodical arrangement of these and other 

 minute Hymenoptera, by Mr. Haliday; who, by the loan of 

 his MSS. and collection, contributed much of the following 

 descriptions : — 



Caput breve, transversum, mediocre, thoracis plerunque latitudine, 

 postice concavum : mandibulae arcuatse, apice bidentatas : max- 

 illae subtrigonae, paullulum arcuatae, lobo terminatae ovato externe 

 piloso ; palpi biarticulati, articulus l us . brevis, 2 US . longus apice 

 setis duabus armatus : labium obconicum : ligula brevis, lata ; 

 palpi uniarticulati, breves, apice setis duabus armati : oculi laterales, 

 minuti : ocelli supra verticem trigone dispositi : antennae 9- aut 

 10-articulatse, geniculatae, moniliformes, vibrantes, corporis longi- 

 tudine aut breviores, vix pubescentes ; articulus l us . linearis aut 

 subfusiformis, longitudine triens : thorax antice et postice angus- 

 tior : prothorax minimus, supra brevissimus, utrinque longior ; 

 mesothoracis scutum maximum, parapsides subtrigonae postice 

 latiores : paraptera trigona : scutelli abdominisque structura 

 varia ; hujus segmenta dorsalia utrinque aciem fingentes segmen- 

 torum ventralium margines amplectentem : oviductus et ejus 

 vaginae 2 laterales lonp-a, graciilima, flexilia, in abdomen dum 



