628 INSECTS AT H03IE. 



dozen large boxes of Muscidas placed before bira,with instructions 

 to find out tbeir names, and to marshal them in their right 

 places. The task really seems to be a hopeless one, and life to 

 be too short for accomplishing it, more especially as there are 

 sure to be some hitherto undescribed species, and they are 

 equally sure to come first to hand, as if for the express purpose 

 of making the unfortunate entomologist hunt for their descrip- 

 tion in vain. At least a thousand species of Muscidse are 

 known to inhabit England, and it is probable that twice that 

 number may be yet discovered and named. 



Fortunately, there is no difficulty in deciding whether a fly 

 belongs to this family or not, as a glance at the proboscis will 

 at once determine its place. This organ is short and mem- 

 branous, and terminated by two large lobes, the structure of 

 which will be briefly described in the course of the following 

 pages. None of the Muscidse are of any great size, the ordi- 

 nary house-fly being of about the average dimensions. 



Without going further into detail, we will begin with the 

 insect which is represented on Woodcut LXXIII. Fig. 3, and 

 which is called Tachina ferox. 



In some respects this insect resembles the ichneumon-flies 

 which have been already described. The female lays her eggs 

 upon the bodies of various caterpillars, and the young larvae, as 

 soon as they are hatched, penetrate into the body of the cater- 

 pillar, and feed upon the fatty substance which was intended 

 to be the subsistence of the insect during its pupal stage of 

 existence. One naturalist reared as many as eighty speci- 

 mens of Tachina from a single caterpillar of the Death's-head 

 Moth. Not only the Lepidoptera, but other orders of insects, 

 are subject to the attacks of these flies, for they have been as- 

 certained to inhabit the larvae of various Coleoptera, Hymen- 

 optera, and even the bodies of spiders. 



The present species has its head tinged with grey, and 

 chestnut hairs on either side. The abdomen is yellowish, and 

 shining as if made of horn, and is black along the middle, and 

 slightly clothed with stiff hairs. The wings are transparent, 

 and tend to yellow towards the base. 



The largest of these insects is that which is drawn on Wood- 

 cut LXXIII. Fig. 4. It is called Tachina grossa, and is so 



