310 Rev. F. D. Morice's Notes on Australian Sawfiies. 



necessitated by the different requirements of their larvae 

 in the matter of food; (2) that in each case it determines 

 in pari the surroundings, and consequently the habits and 

 even the structures of the larvae, and (3) that it requires 

 in each case a different modification in the t ere bra of the $ 

 parent, and of the abdominal segments to which the terebra 

 is attached. It appears also to have another consequence, 

 namely, that it affects the possible distributions of genera 

 and species in the two groups. 



A Siricid larva may be and often is conveyed alive and 

 unhurt from one Region or even Realm to another, under 

 circumstances which would make such transportation 

 practically impossible in the case of a Tenthredinid. Very 

 rarely indeed certain species of the latter group have 

 passed into and become established in a new district other- 

 wise than by their normal methods of dispersal, carried 

 unintentionally by human agency over barriers which they 

 could never otherwise have surmounted, e. g. across sea- 

 straits, and even oceans. Whenever this is known to have 

 happened, it is generally known that their food-plant was 

 transported also.* And it seems almost impossible that such 

 transportation should be successful unless the transported 

 insect happened at the time to have " spun up " or " gone 

 down " for pupation. Neither the exposed larva nor the 

 imago would be likely to survive a violent disturbance of 

 all its normal surroundings, and the life of the latter is 



* In illustration of this two cases may be cited, (a) The Nematid 

 Pteronidea tibialis — an American species — occurs quite commonly 

 in Europe feeding on Robinia psevdacacia, a tree belonging to an 

 exclusively American grouj). This tree was introduced for the 

 sake of its timber on a very large scale by the celebrated William 

 Cobbetti (He sold 40,000 specimens to the then Lord Folkestone 

 for planting, cf. his Rural Hides.) Within a few years it became 

 distributed far and wide, and now abounds in all Western Europe. 

 Not long afterwards the insect made its Hist appearance in England, 

 and was described as tibialis, n. sp. by Newman. Subsequently, in 

 the same year, Hartig recorded it (under another name) as hortensis, 

 n. sp. from Germany. 



( b) The only Tenthredinid common to New Zealand and Aus1 ralia, 

 or to either of these regions and any other, is Caliroa limacina, Retz. 

 Though described from New Zealand as a new indigenous species 

 under the name Monostegia antipoda, W. I\ Kirby, it is undoubtedly 

 the mischievous species whose ugly slimy larva has been a nuisance 

 to all fruit-growers for at least a century and a half, both in Europe 

 and North America, and there can be no doubl whatever that it 

 has reached Australia through the importation of Holarctic fruit- 

 tiees. 



