Pests Affecting Ferns
Green-fly, White-fly, Weevil, Caterpillar, Black Snail.. Slug and Woodlice are the foes that attack, particularly those in a greenhouse.
GREEN-FLY is often due to insufficient ventilation; and better ventilation and an increase of light, if managed without draughts, will often cure the condition.
WHITE-FLY attacks both deciduous and evergreen ferns, but only lays its eggs on the fronds—those laid on deciduous ferns are in due time cleared away—and only the eggs on the evergreen ones are left to develop in the following season. The eggs hatch out in April when larva may be found gnawing away the skin of the foliage. In May the winged insect emerges from the chrysalis and the whole cycle begins again. There is thus a month from the time that notice is drawn to the pest by the dirty white gnawed lines, to the time when the winged creature appears, and in this month the pest must be cleared away. A greenhouse fumigant is used and this disposes of any sti’ay green-flies as well as the white-fly.
The WEEVIL is more difficult to deal with since it can neither be killed by fumigants nor drowned, and in its beetle stage will not succumb to the other insecticides on the market.
As a fat white maggot it devours the root-stocks and roots of the plants and, as a young beetle which emerges from thein April, it eats pieces out of the fronds, the tender young ones preferably. If ferns are found loose in the soil, the pot must be turned out, the roots thoroughly washed to examine the caudex for holes, affected parts cut away, and what is left unaffected may be re-potted. The beetle will come to the surface if the pot is plunged in water, and can then be caught, but it is a night feeder, earth colour, and very cunning, so is difficult to find.
A CATERPILLAR PLAGUE can only be met by persistent hand picking.
Lady Ferns are sometimes attacked by a fly which pierces the stalk of the uncoiling top, and inserts an egg or two. The top wilts and the eggs hatch into two light-blue caterpillars which bore down the stem and into the caudex. If the stalk of the frond is cut off immediately the trouble begins, some inches below the wilted part, the eggs are destroyed, and the trouble stopped.
The SMALL BLACK SNAIL, with an onion-like smell, that attacks the bases of large fronds, can be traced by its slimy track and must be sought and killed.
WORMS and WOODLICE also leave tracks and should be turned out of the greenhouse.
With all deciduous ferns it must be remembered that as they normally die down for the winter, they will require a rest time, and should be cut down when signs of flagging appear, and left somewhat drier—but never quite dry. In the case of pot plants, as soon as new young ferns show their curled brown fronds, they should be repotted.