Pests can move in and take over in the blink of an eye! Fortunately for us, Placer County Master Gardener Gay Wilhelm has some amazing tips for early recognition and removable of pests in the Summer 2010 issue of The Curious Gardener. Before the summer is over, pests can reproduce hundreds of generations, which is why recognizing them and taking control now is an integral part of keeping them at bay throughout the end of the season.
Aphids (left) are a fairly common pest in gardens of all kinds, as they are found on lettuce, apples and squash, just to name a few. They are green, yellow, brown, or red, and pear-shaped with long legs and antennae. If aphids are your gardening nightmare, then you want to look for a influx of ant activity around the plant you think might be in jeopardy. Ants are a warning sign for aphids because aphids excrete a sweet honeydew, which draws the ants toward the plant. Be wary of using fast acting nitrogen fertilizers as they increase aphid reproduction; instead use slow release fertilizer and use it in small amounts.
Next one on the list: the hornworm! If you plan on growing tomatoes this season or have already planted them, this is your enemy. These guys are small brown or cream-colored grubs, and they grow into a long green worm with a horn on their tail, eventually turning into the sphinx moth, which is about five inches across and seen in the early evening. If you have hornworm visitors, you’ll start to see black droppings or denuded leaves. Look for the young larvae around midsummer. Once you’ve seen them the best method for eradication is to hand pick them off the plant, but as this can be time consuming, we also suggest Bt spray. Bt, standing for Bacillius thuringiensis, will effectively destroy the larvae but if you choose this method do take into consideration that Bt will also kill any native caterpillars and butterflies that the spray comes into contact with.
The hornworm photo above is what you’ll see if you have adult hornworms running around. The photo on the right is also of a hornworm but this one may not be such a bad sign. In this instance a wasp has laid its own larvae into the worm’s back. Being a host to wasp larvae will not only kill the hornworm carrying the eggs but wasps are natural hornworm predators, so if you let the wasp larvae continue on their cycle you will decrease your need for Bt spray because the wasps will help in your hornworm eradication.