SlPHONOPHOEA. 
Ill 
these will be noticed to be perforated with a round 
bole, and indeed only empty skins, but others, on 
crushing under a lens, will be found to contain a small 
living grub, which eventually would have become a 
winged Aphidius or one of the like insects. 
In June, during the hot weather, I have seen at the 
same time as many as three of these flies on one rose 
sprig, each poised on the back of an Aphis, which 
throws itself into many contortions for the purpose of 
throwing off its enemy. The ichneumon, however, 
remains fixed on the back for ten or more minutes 
before the ovipositor is thrust under the skin of the 
victim, and the egg is laid. The Aphis appears to 
suffer at first but little, since it soon resumes its 
occupation of pumping up the sap. A wormlike, or 
else more commonly a maggotlike, creature, according 
to the species of the parasite, hatches from this 
egg, which revels in the organised nutritious fluid 
elaborated by the Aphis. The greater part of the abdo- 
men is occupied by this maggot when it becomes full 
fed, and then it may often be seen through the trans- 
parent integuments as a grub curled into a semicircle 
{vide Plate XLIII, fig. 6). In the mean time the 
skin of the Aphis becomes tense and shining, and then 
often shows a peculiar plated appearance, as if a 
numfeer of angular horny plates were united to form 
the dome of the back. Finally, the Aphis dies, the 
grub ceases to feed, and after a certain period of rest 
cuts out of the roof of its prison a circular plate like a 
trapdoor, as regular in form as if a carpenter’s centre 
bit ” had been used. The emerging fly has four wpgs, 
long antennae, composed of numerous joints, a wasp- 
like body and legs, and is in every way suited for its 
marauding expeditions. One of these parasites is 
represented in Plate IV. 
