xx President's Address. [Aug. 28* 



gone far. There she lies dead in my killing-bottle, while I wonder 

 whether I shall be able to classify her. I look at the caterpillar again, 

 and there, busy puncturing, is another Ichneumon, only this one is 

 longer at her work. The fourth puncture is followed by a state of 

 semi-coma. I seize her by the wings and wait, not long ; on comes 

 another, inflicts another puncture, followed by convulsive jerks from 

 the caterpillar. It is time to turn homewards. I consign the cater- 

 pillar to a glass tube. Has the ovipositor touched a nervous centre, a 

 ganglion ? Have the punctures been too numerous ? Is the 

 somnolence of the host caused by the weather ? I cannot find out, 

 but my caterpillar does not outlive its capture more than ten days 

 The parasitic Ichneumon did not probably realise such a result for her 

 progeny. But has she laid all her eggs within one host only ? It is 

 doubtful. Then we have seen several eggs of parasites laid in by 

 several parents ; but, if too many insects lay their eggs in one cater- 

 pillar, it follows that all the grubs cannot get enough sustenance from 

 the host. 



I do not believe that the Ichneumon is able to detect a puncture 

 made a short time before she appears on the scene, in which case it is 

 very probable that the host not affording sufficient nutriment to all the 

 parasites, they will either perish before they can spin the cocoons or 

 be a weak brood, more or less incapacitated from fulfilling their part in 

 the economy of nature — a thing to be regretted, because of the 

 immense services rendered to agriculture by these useful auxiliaries. 



Ichneumons vary much in size, some of them reaching a length of an 

 inch and a half, irrespective of the ovipositor. Some, the Hybrizonites, 

 are so small that they lay their eggs in the bodies of the Rose Aphides. 



The family Chalcididae is composed of an extremely large number 

 of parasitic species more useful to us perhaps than the Ichneumonidae 

 themselves. They are parasites of almost all kinds of insects ; even 

 the Ichneumon are preyed upon by these diminutive flies. I remember 

 trying to rear some caterpillars, the identity of which I was anxious to 

 know. In due time the typical cocoons made their appearance on the 

 back of some of my prisoners. The Ichneumon was rather long in 

 emerging, one did appear at last. No more coming out, I opened the 

 cocoons. Instead of Ichneumons tenanting them I found some 

 Chalcididae, some of them ready to emerge and with the remnants of 

 the skin of the Ichneumon in the cell. The mother Chalcis had 

 deposited her eggs in the cocoons. Some species of that family are 

 even credited with the remarkable habit of laying their eggs in the 

 eggs of other insects. 



The Chrysididoz, or ruby-tailed flies, bear probably the most 

 sumptuous livery in the insect world. No gem can bear comparison 

 with the brilliancy of their teguments. Always in motion, darting 



