400 INSECTS ABROAD. 



the sides of the abdomen, and some spots of the same colour 

 on the thorax. The wings are quite transhicent, except that 

 on the top of the upper wings there are two black spots, as 

 shown in the illustration. It inhabits Australia. 



All the Ichneumonidse are liable to great variation in point 

 of size, and in none of them is this variation so extreme as 

 in the genus Pimpla. Even in the present species, the variation 

 is so great that none but an entomologist would think that 

 insects so apparently distinct could possibly belong to the same 

 species. 



The reason for this difference is simple enough. In its lan'al 

 stage the young Ichneumon feeds upon the larva of some other 

 insect, the victim not being visible to the mother Ichneumon, 

 and therefore permitting no choice. It may be that she happens 

 to hit upon a large and well-fed larva, in which the young one 

 finds ample nourishment, and is enabled to reach the fullest 

 development of which the species admits. But she may happen 

 to hit upon the larva of some small insect, and in that case it is 

 evident that the amount of nourishment must be circumscribed. 



Now, it always happens with insects, that even though they 

 are stinted of food while larvee, they are not debarred from 

 attaining the perfect form, although in such cases they are not 

 half as large as those which have been more fortunate. In fact, 

 I believe that with insects, whether British or foreign, all varia- 

 tions in size are occasioned by the amount of food which they 

 obtain in the larval state. 



On the next page we have another example of the Ichneumons 

 with long ovipositors. 



Even in the present species the length of that organ is very 

 remarkable, but there are some species in which it is very much 

 longer in proportion to the size of its owner. The most astonish- 

 ing of these insects is one that has not yet been described, and 

 which is in the collection of the British Museum. In tliis 

 species the basal half of the abdomen is yellow, and the rest 

 black. Mr. E. Smith kindly measured it, and found that while 

 the length of the insect from the head to the end of the tail 

 is barely one inch, that of the ovipositor is six inches and a 

 half. I wish that I could have introduced a portrait of this 

 most remarkable insect, but, inasmuch as the illustration must 



