142 FERN GROWING 



difficult to eradicate, but appear to do no harm, and they may 

 convey the sperms from one prothallus to another.* They are 

 not found amongst wild prothalli out of doors. Wood-lice 

 {Oniscus asellus) are a destructive pest, as they get under the 

 glass and make themselves nests amongst the seedlings ; they 

 are readily seen and removed ; a saucer of water surrounding 

 the seed-pans is an effectual barrier. 



The crane-fly, or daddy-long-legs [Tipula oleracea), is 

 sometimes a pest, especially in the Biinter formation, where 

 in July and August (as in Nottingham Park) the winged 

 insect is seen in millions. 



Beetles never troubled the author. Birkenhead's beetle- 

 traps will catch them ; but not wood-lice or slugs. The grub 

 of the weevil [Curculio sulcatus) is exceedingly destructive 

 to young Scolopendriums, and even to fully grown plants ; 

 they feed on the roots until none are left and the plants 

 are dying before their ravages are found out. The only 

 plan is occasionally to pull at the fronds, and if they are 

 attacked by weevils, one or more will be found disconnected 

 with the plant. When this is the case, all the soil must be 

 shaken off, and the grubs found and destroyed. A hunt 

 should be made for the perfect insect, as it is often detected 

 in the daytime resting on the sides of the pans, or hidden 

 under the leaves ; at night it may be found crawling about. 

 Some years this weevil is much more destructive than' in 

 others. In the spring of 1890, on new soiling a bed of Aspi- 

 diums, many thousands of these grubs were found. On taking 

 up the large plants and shaking off the soil, it was seen they 



* Amongst these Podura plutnbea (skipjack), of the order Thysanura, family 

 PodurellcB, evidently carries the male sperms of Ferns from one prothallus to another, 

 and thus causes a strange impregnation. This insect was seen under a bell-glass that 

 protected a division of a prothallus that had lived six and a half years without pro- 

 ducing fronds because it had only the female organs, but three weeks afterwards a 

 frondlet appeared. It is not only remarkable that a prothallus should live six and a 

 half years, but that it should be in a condition for impregnation. 



