103 



rhizome ; the adults externally, gnawing the surface of the frond 

 and consuming the abraded particles. The leaves are often eaten 

 from the edge. The damage suffered by the plant depends upon 

 the severity of the attack, which in turn will be relative to the 

 excess or poverty of weevils according to the conditions for their 

 multiplication. It has been observed that while plants may be 

 badly shattered as the result of the attacks of the weevil, they 

 do not readily succumb, but linger on in a stunted condition for 

 long periods. 



The evidence at hand indicates that the progress of disper- 

 sion in the case of the fern weevil is comparatively slow, when 

 human interference plays no part in it. In fifteen years the 

 weevil extended its range less than five miles in the mountains 

 back of Honolulu. The advance was presumably more rapid at 

 Hilo on account of the greater abundance of ferns. Being en- 

 tirely without wings, the weevil is flightless, and its only means 

 of locomotion is crawling. It also appears to remain inactive a 

 large part of the time. These two factors are undoubtedly 

 responsible for the slow progress before mentioned. Human 

 activity, however, forms an important feature of the dispersion. 

 The transportation of ornamental plants from one locality to 

 another seems to be the chief means of distribution of this 

 weevil, and extraordinary distances are often thus traversed. 

 The weevil also readily attaches itself to clothing, the hair of 

 animals, etc., and by this means can be carried far. 



Life History. 



The fern weevil exhibits in its development what is known as 

 complete metamorphosis ; that is to say, there are four distinct 

 stages in the life-cycle of the insect, namely, the tgg, larva or 

 grub, pupa and adult. 



The egg: The egg of the fern weevil is elliptical, smooth, 

 pale yellow, 1 mm. long (PI. I., figs. 1 and la). It is placed, 

 singly, .5 mm. below the surface of the fern stipe or stem, in a 

 cavity previously eaten out by the female weevil. After the 

 deposition of the egg, the external opening of the cavity is 

 closed with frass. The incubation period is about 9 days.- (See 

 Table I.) (All rearing and other life-history work done in the 

 entomological laboratory of the Board of Agriculture and For- 

 estry at Honolulu. The data here given applies only to this 

 locality.) 



The larva: The larva on hatching is about 1^ mms. long, 

 creamy to sordid white, the head a little darker, the heavily 

 chitinized mandibles, especially on the cutting edge, dark brown. 

 There are conspicuous hairs on the plate behind the labium, at 

 the apex of the ultimate, and on the dorsal surface of the penul- 

 timate segment. The larva molts several times during the course 

 of its growth, each time increasing in size. The full grown larva 

 is 8 mms. long when crawling, 6 mms. long when curled. It is 



