OCCASIONAL ABUNDANCE OF INSECTS. Bul 
been suggested to account for these years of abundance. 
That is the retarded development or “‘ laid over”’ theory, 
as itis called. This assumed that the development of the 
pupe of gal sometimes, in fact generally, owing to some 
mysterious influences is retarded for years. There is no 
invocation of continental swarms here. D. galivis always 
with us but generally in the pupal state, then once in a 
long series of years, owing to some influence equally 
occult, pupal maturity arrives and with one accord the 
long lost moths emerge into the light of day. 
Now this theory might be debateable were there any 
parallel case known in the whole insect world; but besides 
the fact of the supposition of pup lying buried for 18 
years being utterly inadmissible and unsupported by one 
scintilla of evidence, the idea only lands us in a still denser 
jungle of inexplicabilities. It is difficult enough to ration- 
ally explain why galw should turn up at an 18 years 
interval, but the introduction of mysterious influences 
which retard the pup, and defer or compel the emergence 
in certain years of the imago does not tend to make things 
any clearer. It is true that the monstrous assumption 
has been ventured upon that the sufficing cause is the 
very structure of those hills of sand among which the 
insect in most places lives. The idea is that the sandhills 
move, cover up the pupe and preserve them until such 
times as some further or retrograde movement of the sand 
uncovers those pup and liberates the imprisoned moths. 
Now that these masses do move owing to peculiar wind 
action is certain, no less certain is it that did a thousand 
tons of sand or so move bodily and heap itself up over any 
congregation of buried pups, such an obstacle would defer 
the emergence of the imagines; but not for eighteen years, 
the deferment would be for all time. No resurrection 
morning would ever come to those pupe. I indeed 
