IHIS ENTOMOLOGICAL SOCIETY. 47 



a general application of these measures in infested areas to all trees upon which 

 the pest can subsist would mean its early control and practical elimination so far 

 as material damage is concerned. Residents of the infested section are most- 

 strongly advised to watch for the development of the insect next season and to 

 spray all trees showing signs of its work, since it is very important to control it_ 

 so far as possible, because experience has demonstrated that it is easier to handle 

 an outbreak in its incipiency than to begin after serious losses have occurred. 



SOME NOTODONTIAN LA-RV^. 



Eev. Dr. J. A. CoKCORAN, Loyola College, Montreal. 



The sudden appearance of temporary structures and protective colours and^ 

 markings of caterpillars are usually attributed to the action of stimuli from with- 

 out. Whether this deduction will remain unshaken by the facts that the observers 

 of the future may bring to light, or will be discarded, does not concern us. It is 

 sufficient that this theory gives the entomologists of the present day a spur to 

 observe more closely the changes which various larvae undergo before reaching the 

 stage of pupation, and makes of their observations the solution of a definite 

 problem instead of the compilation of a catalogue of uncorrelated changes. Eor 

 the external stimuli which have acted in the past must be more or less active to-day, 

 otherwise the structures they have produced will become useless and vestigial, 

 since God in His goodness does not allow a creature to retain a structure, that is a 

 functioning structure, which has become really hurtful to its possessor. 



In an endeavour to find a cause for the abrupt appearance of certain colours 

 and temporary armament in the Notodontian larv^, I had under close observation 

 last summer some colonies of Schizura concinna and Heterocampa guttivitta. My 

 observations of the habits of these larvae were too restricted, and my microscopic ex- 

 amination of the sections of the parts before and after the changes were too super- 

 ficial, to be of value in arriving at a definite conclusion, but I give them in the 

 hope that some of our members may find them of interest and later when the win- 

 the-war problems no longer call for the entomologist's undivided attention, they 

 may record their own studies on the larvae of these same species. 



When first seen the larvae of S. concinna were about 3 mm. in length and 

 arranged themselves in serried ranks on the under surface of the leaves of an apple 

 tree. I divided the colony into two, leaving twenty larvae undisturbed and placing 

 the rest on a nearby branch of the same tree, so that I might have material for 

 dissection while not depopulating my observation colony. The moth had deposited 

 her eggs on the end leaves of a branch most conveniently placed where they could 

 be seen at all hours of the day. 



During the first stage the larvae fed on the epidermis and tissue of the under 

 side without puncturing the leaf, and hence could not be seen from above. Their 

 yellowish heads which were smooth and unarmed, and their yellowish-green bodies, 

 tinted reddish along the sides, harmonized so well with the surface on which they 

 fed that it was difficult to distinguish them. Neither insects nor birds seemed to 

 spy them, although a dozen two-winged flies passed within a few feet of them, and 

 an aphis lion was seen running about on the lower part of same branch on which 

 the polony fed. The third day after discovery all the members of both colonies 

 moulted and passed to the second stage. 



