INSECTS 



BRACONIDAE 



A brief introduction to the Braconidae may be interesting, to show how or why they are 

 separated from the true Ichneumonidae. It is by the neuration of the fore wings ; these have the 

 exterior discoidal transverse nervure wanting, and by having the first cubital areolet generally, though 

 not always, separated from the praediscoidal, and the entire absence of the small areolet. The 

 Braconidae perform the same function in nature as the Ichneumonidae, and are related to them in 

 structure and habits, and like them the ovipositor may be of any length ; that is, be as long or 

 longer than the body, or it may be hidden. 



The larvae vary in their habits when preparing for the change to the pupa stage, as much as, 

 if not more than, the Ichneumons. Some attack small half-grown larvae, others the largest larvae ; 

 some attack adult beetles, some the beetle larvae ; in fact nothing appears too large or too small in 

 the insect world to escape their attention. 



Many species do not leave their host to make their change to the pupa, but remain within the 

 skin of the larva, until the fly is ready to take flight, when it cuts a hole and escapes. The habits 

 of the larvae of the Microgasteridae are quite the reverse of those just mentioned. Without any 

 exception they leave their host and spin silken cocoons, very much like that of the silkworm moths 

 of commerce, of course in miniature. 



Some larvae are solitary in their habits, while others are gregarious ; as many as 1 80 may 

 emerge from a single caterpillar, each one making a separate cocoon, or make an alveariform mass. 

 One particular species, Apanteles formosus, builds up a stem, on the top of which the cocoon is made. 

 The way the alveariform mass is made may be worth recording. The writer was present on one 

 occasion when ninety-five larvae of Microgaster flavipes had just commenced to emerge from an 

 unfortunate caterpillar of Boarmia gemmaria, each one making a hole for its exit, all trying to escape 

 at the same moment. This wriggling mass of maggots at once commenced to spin silken cords. The 

 caterpillar at this time was stretched out full length on a privet twig ; the spinning of the maggots 

 continued, and it was three hours before any form or order could be detected, whether they were 

 going to make a round mass or the usual semi-pyramid of cocoons. From that time it began to get 

 into the final shape, and was completed, to all external appearance, in about seven hours. The mass 

 was formed under the twig. The caterpillar by that time had twisted itself half round, apparently 

 trying to protect its destroyers ; by the next morning it had taken up a position over the cocoons, 

 just as a hen would over a brood of chickens. 



The Aphidiides are solitary parasites. The larvae generally remain in the body of the Aphh, 

 ' green fly,' the whole of the changes taking place within it ; when the fly is ready to escape, it cuts 

 a circular hole in the body of the dead Aphis, and flies off. 



In the genus Praon the parasite, when full grown, emerges from the body of the Aphis on the 

 underside, and spins a tent-like cocoon ; the dead Aphis remains on the top long after the para- 

 sitic fly has escaped from the cocoon. 



Small as these must be when the whole of their sustenance was obtained while living within 

 the body of an Aphis, few would imagine that the continuity of the hyperparasite depends on the 

 female {Allotria) discovering an Aphis already infested with a parasite wherein to deposit her eggs. 



It may be interesting to know how this last observation was obtained. One bright sunny 

 afternoon, while the writer was on the search for Aphides infested with parasites, his attention was 

 attracted to the actions of some small flies, who evidently were on the same business as himself. 

 The infested Aphis are readily detected by their brown, hard, dead-looking bodies. These small 

 flies were paying great attention to the infested Aphides by constantly applying their antennae to 

 several parts of the body of the Aphis. When one of the flies had ascertained it was a suitable 

 subject, she commenced depositing her eggs within it. Having watched these manoeuvres for some 

 time, one was selected that was seen to deposit eggs, she was brought home, also the Aphis that the 

 eggs were deposited in. A week or two after two flies emerged, the offspring of the parent that 

 deposited the eggs [Allotria victrix). The larvae of the two flies that were bred fed on the single 

 larva that had consumed the Aphis. 



CYCLOSTOMI CYCLOSTOMI {continued) 



Braconides Braconides {continued) 



Genus, Bracon Genus, Bracon 



— erythrostictus, Marsh. Bred from gall on Lyme — nigratus, Wesm. Horrabridge, June ; Bickleigh, 



grass, Psamma arenaria July 



— fulvipes, Nees. Bickleigh, Telverton — stabilis, Wesm. Bred July from Sciaphila 



— longicoUis, Wesm. Bickleigh, July ; Oreston chrysantheana 



Quarry August — erraticus, Wesm. Plym Bridge, Bickleigh, August 



variegator', Nees. Bred 7 July from Gelechia — Roberti, Wesm. Braunton Burrows, T. A. 



pinguinella Marshall 



181 



