100 



of some other and rarer species of Odyncrus, its occurrence with spinipes 

 being accidental in the same sense as that of C. ic/nita may be said to be so. 

 When making our researches last summer with a limited supply of materials, 

 we were unable to detect the eggs or larvre of Chrysidcs, though we felt satis- 

 fied that one or other must be present in a certain proportion of cases. What 

 was sought for, we being guided by what was then known of their history, 

 was a Clirtjsis egg beside a feeding larva of spinipes, or the larva of Chrysis 

 attached to the latter. This we were unable to find simply because such a state 

 of matters at no time e\;ists, vet we found cocoons ot Chrysis. and one of these, 

 which we now know to be that of 0. neglccta is figui-ed in Ipst year's Trans- 

 actions of this club. During the winter a number of nests of Odynerus 

 spinipes were investigated with the result of finding three diS'erent kinds of 

 cocoons of Chrysis. These cocoons were in the proportion of one to three 

 of those of the wasp, giving the measure of the destruction caused by 

 these parasites. Three-fifths of these cocoons were similar to that figured, 

 and they produced Chrysis ncfflccta. Each compact oval cocoon was enveloped 

 in loose sUk filling up the space space in the cell of spinipes, the only frag- 

 ments observable being those of the little green grubs wliich ai'e stored by 

 the wasp after her egg has been laid. Two-fifths gave birth to Chrysis 

 bidcntata, and these cocoons were of a much more curious structure, each 

 being contained in a cocoon of sjmiipes, clearly showing that the Chrysis larva 

 did not destroy the wasp larva untU the latter was fuU fed and had been spun 

 up. The cocoon proper occupied the lower half of the cell, its roof being an 

 almost miiTor-like diaphragm across the centre of the cocoon of spinipes, the 

 walls of which above the diaphragm were also covered by a layer of silk spun 

 by the Larva of Chrysis. The third kind of Chrysis cocoon was a solitary speci- 

 men out of more than a hundred, and produced Chrysis ignita. This cocoon is 

 longer and slighter than that of Chrysis nec/lecta, and of a darker colour'. 



Following up the clue afi'orded by these cocoons, I have this summer 

 succeeded in observing the whole economy of Chrysis bidentata, much of that 

 of Chrysis neglecta, and by a lucky accident some of that of Chrysis ignita. 



Chrysis neglecta begins to emerge from the pupa state at the same time 

 as Odynerus spinipes, namely, about the middle of May, and by the first week in 

 June all of both species of insects have emerged. On examining a bank 

 abundantly colonized by Odynerus spinipes at this period the cocoons of the 

 previous year are found empty,' but Chrisis neglecta will often be found hiding 

 away, if the day be dvdl, in the empty cocoons of spinipes and usually two in 

 each cocoon. When the sun is out spinipes is busy constructing her canals 

 and granular tubes and Chrysis neglecta actively running and flying about the 

 burrows. Chrysis bidentata is not to be seen, and on careful examination it 

 will be found that the cocoon of this parasite of the previous year still con- 

 tains the perfect Chrysis bidentata, which does not emerge until the last of 

 the spinipes brood are coming out, about three weeks later than Chrysis 

 neglecta, I have not seen the egg of Chrysis neglecta, and do not know where 



