80 THE CANADIAN JiNTOMOLOGIST 



Achorutes humi Folsom and Neanura muscorum Templeton oviposit late in 

 the fall. The eggs of the last-named took 35 days to hatch at an average 

 temperature of 60 F. This is a remarkably long period compared with the 10 

 or 12 days required by the eggs of Achorutes socialis under the same conditions; 

 and in the insects' natural habitat incubation would doubtless have been even 

 longer, for the young Neanura appeared in my bottles on the 8th January; and 

 in their native wilds, sheltered from the intense frost only by the bark of a 

 rotten log, it is scarcely likely that they would have hatched before spring. 



On emergence from the egg, the young of a two millimeter adult are about 

 one quarter of a millimeter long, and are invariably white, with — except in the 

 blind species — conspicuous black eye spots. They are perfectly' developed, 

 but are not of quite the same proportions as the adults, — being somewhat 

 shorter and thicker — and are wonderfully active runners and jumpers. Their 

 growth seems to be slow, but it is scarcely safe to generalize on this point from 

 the progress of the young in captivity, for they do not thrive under artificial 

 conditions. Achortites socialis and Achorutes packardi captured when well 

 grown, have lived for six to eight months in my vials, and it was more than a 

 year before senile decay carried oiT Xenylla maritima. But though I have seen 

 the young of half a dozen species hatch out, not one of them ever survived 

 longer than two or three weeks; and during this brief life I could never notice 

 any marked change in their appearance. 



Some species at least are sexually mature a good while before they attain 

 their maximum size. Achorutes socialis reaches a body length of two milli- 

 meters, but specimens only one and a quarter millimeters long lay eggs. The 

 number of moults, so constant with many insects, is I suspect with them in- 

 definite, for they seem to keep on shedding their skins and growing as long as 

 they live. The largest sized specimens of several species that I am familiar 

 with are found only in the spring. Apparently belonging to some brood of the 

 year before, in spite of the almost sub-arctic cold of this district, they have con- 

 tinued to grow all winter in their shelters under the snow. 



Their food seems to consist of organic matter of almost any kind. They 

 have been found feeding on dead molluscs, fish and birds along the shore, but 

 probably vegetable substances supply most of their nutriment. The mandi- 

 bulate mouth-parts possessed by the majority are obviously designed for chewing. 

 Some of the species I have had under observation fed on rotten wood, moss and 

 lichens; others — notably the Arthropleona — would not eat at all in captivity. 



No matter how small you are, trouble won't overlook you, and even the 

 minute springtail has its enemies. Lubbock and some others refer to the presence 

 of Protozoa in the internal organs of Collembola, and Imms found Nematodes 

 in Anurida maritima. Nor are external parasites wanting. Of twelve or fifteen 

 specimens of a small Sminthurus I collected last summer in the long grass 

 of a beaver meadow, five had still smaller red mites firmly attached to them. 

 This genus seems to be subject to attack by mites, for Lubbock mentions the 

 same occurrence in connection with S. fusee (L.). Other likely enemies of the 

 Order are the tiny spiders and chelifers, the thread-legged bugs and other pre- 

 daceous creatures that one often finds in the coUembolan habitats. 



