0Controlling pests on indoor plants

I grow toma­tos, cucum­bers, chil­lis, lem­ons and olives in a south facing con­ser­vat­ory.  Over the last 5 years I’ve suffered with a range of ver­min attack­ing my plants, it seems to be a dif­fer­ent type of pest each year after I’ve conquered the pre­vi­ous pest.  Below I cov­er a few suc­cess­ful ways I’ve found to con­trol a range of pests.

General advice

I’ve found that some vari­et­ies of each type of plant are much more res­ist­ant to ver­min than oth­ers.  For example the F1 Aji Limon chilli pep­pers don’t seem to be tar­geted much by any ver­min, so I now tend to grow these rather than oth­er chil­lis.  If all else fails then I recom­mend look­ing at the vari­et­ies you are grow­ing and try some dif­fer­ent ones.

Red spider mite

Red spider mites are one of the worst pests as they seem very dif­fi­cult to des­troy.  They are fairly res­ist­ant to most sprays and treat­ments.  I have found a few approaches effect­ive.  The first is to grow a few pots of chives both inside the room, and in the garden.  Red spider mites appar­ently are repelled by the smell of chives.  The second con­trol I have used is pred­at­ory mites that eat red spider mite.  Red spider mites also like a room to be dry and hot so I have allowed the room to get colder at night (e.g. by leav­ing a small win­dow open).

Greenfly & Blackfly

Green­fly and black­fly are com­mon pests that can attack most plants and mul­tiply extremely quickly.  How­ever they are real­tively easy to kill.  Mild soapy sprays eas­ily kill them off, but to avoid using even this I usu­ally obtain some lady­bird and lacewing lar­vae around April-May and these will eat through green­fly in short order.  Green­fly and black­fly also don’t like dir­ect sun so I have replaced my drain­age trays with light col­oured ones and repainted the room to a light­er shade so that more reflec­ted light hits the under­side of the leaves.

Thrips

Thrips are also eaten by lady­bird and lacewing lar­vae so the same treat­ment for green­fly and black­fly seems to help keep thrips under con­trol.  Keep­ing a win­dow open also allows the adult lady­birds and lacewings to escape into the garden where they will hope­fully help to increase to loc­al out­door pop­u­la­tion, which in turn should reduce the sup­ply of new pests in future years.

Mealybugs

I’ve had these on my lem­on tree but not on any­thing else.  They are par­tic­u­larly fast at repro­du­cing, and seem to attack the form­ing fruit, killing it off.  They can be dealt with by a range of bio­lo­gic­al con­trols includ­ing lady­birds and lacewings.

Scale

This year I’ve had scale insects on my olive plant.  As with all pests I have ini­tially treated them by pick­ing them off and squash­ing them.  There are 3 vari­et­ies of para­sit­ic wasp (Meta­phy­cus hel­vol­us, Meta­phy­cus bart­letti, and Scu­tel­lista cyanea which are all harm­less to humans) that will con­trol scale insects.  The first 2 of the 3 are only suit­able for indoors, whilst the 3^rd does­n’t seem to be widely avail­able.  They are most effect­ive with soft scale insects.  Hard scale insects are best addressed with a type of lady­bird — Chilo­cor­us nigritus.

General advice

The large major­ity of pests seem to be sus­cept­ible to lady­birds, lacewings, and pred­at­ory wasps.  The best thing for your garden is to sup­port nat­ur­al pop­u­la­tions of these help­ful insects by provid­ing them with access to a suit­able hab­it­at and water.

What next?

I’m anti­cip­at­ing yet anoth­er new pest next year, per­haps I’ll get some vine wevils on my out­door grape vine.  Whatever comes I’ll be ready.