188 MR. C. B. HARDEXBURG 



midribs, as also tlie flower stalks of the '' svringa," 

 Mel'wa azcdarachy possessed all the qualities for making 

 satisfactory momits; they do not split, do not corrode 

 the pin, and grip the pin tightly. They are best col- 

 lected for this purpose in the autumn when the leaves 

 ^re about to fall. A piece of suitable diameter is in- 

 i^erted into the hollow of the straw which projects beyond 

 the larva and then the mounting pin will have a firm 

 ]iold. 



These syringa sticks can also be used for the double 

 mounting of the minute larvae, the glass tube being 

 pushed into the pith of the syringa and the mounting 

 pin pushed through the latter. 



The Breeding of Caterpillars. 



With the collecting and preparation of those cater- 

 pillars which we happen to find in the field we have not 

 completed the life history of the species. The caterpillar, 

 having a hard, inelastic chitinous skin, is capable of ouh' 

 limited growth, after which the skin becomes too small. 

 Then a new skin is formed underneath, and the old one 

 splits and is stripped off. This process is called moulting 

 and the stages preceding these moults are the correspond- 

 ing instars. Thus, the stage between the time the eg^ 

 hatches and Ihe first larval moult is the fir.st instar, that 

 between the first and second moult the second instar, 

 and so on. The cast skins are called exuviae. A 

 caterpillar goes through several moults before pupating 

 and the various instars are often quite different in ap- 

 pearance, i.e., in colouration, ornamentation, and arma- 

 ture. The des(iij)tion of a cater])illar in a certain 

 instar may thoi'of^u'e not fit the species at all in the pre- 

 ceding or following instar. Now it is very seldom that 

 we have the opj)ortnnity of watching a caterpillar in 

 the oi>en on its food-i)lant during its entire larval life 

 and of collecting samples of each instar. To obtain these 

 it is necessary to breed the cater])illar in a place where 

 it can be kept under continuous observation; that is, in 



