Boxelder Bug

The Boxelder bug, Zug, or Maple Bug (Boisea trivittat) is a supremely annoying insect which can be found on or near  Box Elder (Acer negundo), other Maples, Ash, and Goldenrain Tree (Koelreuteria paniculata). Adults about a half inch long and mostly dark brown or black, with red veins or markings. Nymphs are mostly red.These bugs are similar in appearance to stink bugs and can put off an order if they feel threatened.

They are not known to be particular distructive and are not considered an agricultural threat. But let me tell you from personal experience that these bugs congregate in the hundreds on hardscape, door frames, etc. near their host trees and can be quite a nuisance. I have only just noticed these pests in large number recently, but they can be active outdoors from spring through fall. They also hibernate in walls and behind siding through the winter.

*Update: 30 minutes after I posted, I noticed a Zug walking across my desk! My office walls have been breached.

tomato hornworms

This year I became acquainted with a new garden pest, the Tomato Hornworm. This large bug is actually a caterpillar that chomps away on tomato plants, in a perfectly green disguise. My first clue they existed was actually the frass (bug poop), because it is dark and stands out against the leaves. The ‘horn’ is fake, and meant to scare predators.

These bugs can defoliate an entire tomato plant overnight, so let’s discuss prevention and control. One way to prevent these pests is to cultivate the top few inches of soil wherever tomatoes have/are being grown. This will expose the pupa to predators, like birds. It’s helpful to have a birdbath in the area where your tomatoes are growing.

Another environmental control are parasitic wasps (Braconidae) that lay eggs, hatch, and spin cocoons on the backs of the caterpillars that end up looking like grains of rice. These tiny wasps slowly eat the caterpillar as they grow into adults. If you find a caterpillar covered in these cocoons, place the bug and some leaves in a jar with large-holed screening to enable the wasps to escape and infect more caterpillars.

I have only seen a few of these caterpillars (each with the parasistic wasps present), but should the issue become worse, the next phase of control is targeted insecticide. Bt (Bacillus thuringiensis kurstaki) is a naturally occurring bacterium which targets caterpillars specifically. After eating the Bt sprayed leaves, they lose the ability to feed and die within a few days.

Bt is one of the safest insecticides on the market, sold under the names ‘Dipel’, ‘Green Step’ etc. and is certainly preferable to broad-spectrum insecticides. Lady Bugs and other beneficial insects will not be affected, and neither will the birds that eat caterpillars who have consumed Bt.

Some plant damage on plants has to be acceptable when gardening in an eco-friendly way; the Tomato Hornworm is after all the larvae of the Five-Spotted Hawkmoth (Manduca quinquemaculata). But, if you are dependant on your tomato crop for food, spraying Bt every few weeks will prevent crop loss and is an environmentally sensitive means of pest control.

The image above is a Tomato Hornworm parasitized by wasp larvae.

Bugs Be Gone!

In an effort to use fewer chemicals in all aspects of gardening, I have been testing two natural bug repellents. Repel Lemon Eucalyptus insect repellent spray (for skin and clothing), and Bug Band insect repellent band (which you can wear on your wrist, ankle, belt loop), both sold by REI for $9, and $5, respectively. So far, I’ve had good results, with no bites; but not without noticing strong smells.

Both of these products utilize plant derived repellents. The Lemon Eucalyptus is a natural bug repellent that I could only find at REI, after reading lots of promising research data on-line. The bug band uses Geraniol, derived from Geranium, which is a fairly common ‘natural’ bug repellent ingredient.

Lemon Eucalyptus is touted to be as effective as DEET for a short periods of time. Once applied, the odor is more pleasant than DEET, but still quite pungent. The bug band also has an odor, not as pleasant as the eucalyptus spray, but not as strong either. The advantage to the band is that can be removed easily, though traces of the scent linger. (I've been wearing the band around a belt loop.)

As someone who works outside frequently, I take the health risks posed by ticks and mosquitoes very seriously. At the same time, I want to limit my exposure to chemicals, like DEET, which may affect the nervous system. These plant-based options seem to be a good balance between effectiveness and healthfulness.

The photo is one of my Hollyhocks, which have been in bloom for several weeks now.