As the July and August heat sets in there are several pests that come out with it. I’ll be discussing the life cycles, damage, and ways to control five of these pests. In this article, I’ll discuss the squash bug, cucumber beetle, Japanese beetle, squash borer, and tomato hornworm. Let’s get started!!
Anasa tristis, commonly known as “squash bug”, is a large insect around half an inch in length. They tend to have a flattened look to them and have colors ranging between gray, brown, and black. They look as if they are wearing a protective armor shield due to the sharp angles they can have protruding from just behind their head. Squash bug eggs are elliptical, having anywhere from a yellow tint to a golden red color. When the nymphs hatch they are very small, about 1/10 inches in length. When they are born they have a green abdomen with a black head and legs. As they mature they turn a light gray, almost blue, and progressively become more brown and black. They also develop antennas.
As adults, squash bugs overwinter in sheltered places such as under plant debris, around buildings, or under rocks. In the spring they start flying to cucurbita plants to start feeding and mating again. The females lay their eggs in clusters of around twenty. They tend to lay on the underside of leaves between veins. They may also lay on top of the leaf, usually right where the stem meets the leaf. They start their laying in early June and continue through mid-summer.
Nymphs hatch in about ten days, and mature after four to six weeks. Only one generation develops each year, however there is a partial second generation some years. Their stages overlap and they can be seen at any stage throughout the season. At the end of the year the bugs tend to congregate on the squash fruits once the plant is dead. Before the plant dies they tend to stay close to where the main stem meets the soil, and even hide in mulch surrounding this area.
Squash bugs have piercing-sucking mouthparts that are used to suck the sap out of leaves. This causes yellow spots, which eventually turn brown. This damage in turn disrupts the flow of water and nutrients, which might cause wilting. Young squash plants are more susceptible to damage and could die from intense feeding by the squash bug, but larger healthier plants are more tolerant of feeding damage.
To stop squash bugs it is very important to pay close attention to your plants when they are young and also when they are flowering. Once squash bugs appear, the first thing you can try yourself is to find them and squish them between your fingers. This is my method, and is by far the fastest and easiest. For those who can’t stomach smashing a bug between their fingers then you can carry a cup of soapy water with you and drop them into the cup. Squash bugs can be slightly humorous to catch because when they see your fingers coming at them, they go into stealth mode and try to side step around the stem they are perched on. Have your other hand ready to snag them up as they dance around the plant. When I find eggs I crush them the same as I do the adult bugs (which I also do for the nymphs). Do not throw eggs on the ground because they will still hatch and find the plant. You can also toss the eggs in a zip lock bag and crush them through the bag or place them in some soapy water. You may also try trapping the bugs at night by laying out boards or pieces of newspaper. They congregate there at night so that early in the morning you can catch them all huddled together. For those not wanting to touch the bugs, or for major infestations I recommend using Earth-tone Insect Control spray, Pyrethrin concentrate, or Safer Insect Killing Soap.
Be warned, if you find one squash bug, you’re bound to find a second!
There are two types of cucumber beetles that are pests in the garden. One is about a quarter inch in length and has three black lines and four yellow running longitudinal. The spotted cucumber beetle looks more similar to the lady beetle. It is spotted with twelve black spots against its yellowish wings. The larva of the cucumber beetle is white, and around three eights of an inch long. It dwells in the soil around the roots of the cucumber plant. The eggs of both cucumber beetle species are a pale-orange-yellow, and are laid in groups near the base of cucurbita plants.
Adult cucumber beetles overwinter in protected locations similar to the way squash bugs do. Early in the spring they start feeding on blossoms and leaves of both cultivated and wild plants. Once the adults find cucurbit plants the females lay groups of eggs at the base of the plant. The larvae of the egg develop for two to four weeks on the roots, pupate in the soil, and appear as adults in early to mid-August. The spotted cucumber beetle migrates to the northern U.S. and Canada each year.
Heavy infestations of adult cucumber beetles can destroy stems and emerging leaves of young plants. A mature plant’s blossoms and fruits can also be damaged. The larvae of the beetle can also avail the roots to become more susceptible to disease by feeding on them. Bacterial wilt can also be transmitted to cucurbits from cucumber beetles.
For controlling these pests try using row cover early in the season. You can also use individual screens or cones for young plants. Remove any plant that is infected with bacterial wilt. For the adult beetles I recommend the ol’ capture and squish ‘em with your hand method. Effective insecticides that we carry include Pyrethrin concentrate, Earth-tone Insect Control spray, Neem Concentrate, and Neem spray.
Japanese Beetles hail from, yes you guessed it, Japan. They are usually less than half an inch long. They are a bright metallic green with copper-brown wing covers. In early June they start to emerge from the ground, feeding on just about anything. They stick around for 30-45 days. During this time the female will lay around fifty eggs in the soil. The grubs hatch around eight to fourteen days later. The grubs then spend the next ten months underground feeding on plant roots and organic matter.
The Japanese beetle prefers plants in full sun and they do not like to dine alone. They emit pheromones in places they like, which then attract more Japanese beetles. If you are able to catch them early on, hand squishing them can be an effective control, as well as dropping them into a cup of soapy water. The beetles are less active in the morning which makes this the best time for killing them. Organic insecticides include Milky Spore (which kills the grubs, and remains effective in the soil for 10+ years!), Earth-tone, and Pyrethrin concentrate. If you let the beetles go unmolested they will very quickly devour the plants they prefer. We carry Japanese Beetle traps which are certainly effective at catching and killing, although some folks say they attract beetles which otherwise wouldn’t be present.
The squash vine borer is another pest of the Cucurbita genus. The caterpillars can reach a length of one inch. They tend to be white or a creamy white with a brown head, and they bore into the stem base of cucurbit plants. The adult borer is a stout dark gray moth with hairy red hind legs. The insect overwinters as a full grown larva or a pupa one to two inches below the soil surface. The larvae pupate in the spring. Moths emerge about the time the plants begin to run, and moth flight lasts until mid August. They lay small brown eggs on the leaf stalks and vines which hatch in seven to ten days. This larva will immediately bore into the stem. It will then continue to feed for fifteen to thirty days before it exits to pupate in the soil. There can be up to two generations in a year.
The way you find the borers is by spotting what looks like slimy sawdust or pollen hanging off the vine of the plant. Once you find this gunk, you should be able to then see which direction the damage is going. The point where the damage stops is where the borer most likely is unless it has left the plant. The best way to maybe save your plant is to use a sharp knife to cut a slit up the vine. Then wedge apart the slit you just created and look for the borer. Take it out with a pin or needle and squish it- be careful though these guys are juicy! After the borer is removed, cover the area of the vine that was cut open with soil so that new roots can emerge. There are no effective organic sprays that we know of, but there are several DIY measures that you can take. Look for eggs in the spring and crush them, make a tin foil collar around the base of the plant where it meets the soil, and make sure you compost the plants at the end of the year in case they still contain borers waiting to pupate.
Unlike the Japanese Beetle, the tomato hornworm (Manduca quinquemaculata) is native to the U.S. Hornworms feed on solanaceous plants, most often tomatoes, but also eggplant, pepper, potato, horse nettle, jimsonweed, and nightshade.
The adult moth is a large heavy bodied one that is gray with brown coloring covering the wings and body. The wings can spread four to five inches wide. The moths lay eggs on both the upper and lower surfaces of leaves in late spring. The eggs hatch in six to eight days and are oval, smooth, and light green to yellow in color. The larvae are green with white and black markings. There is black projection on the last abdominal segment which gives this caterpillar its name “hornworm”. Fully grown larvae will drop off a plant to burrow themselves into the soil to pupate. In the summer they will emerge from pupae in about two weeks. The moths will then emerge from the soil, mate, and start depositing the eggs of the next generation on tomato plants. In early fall the pupae will remain in the soil, where they stay all winter and emerge as moths the following spring.
The larva is the stage at which this pest does its damage by feeding on the upper portions of leaves, leaving a trail of dark green or black droppings. Older larvae are capable of destroying several leaves as well as fruit.
For control there are several things that you can do. One is to handpick the hornworms. If you find one that has tiny white sacks all over it then let it be, the sacks are beneficial braconid wasp eggs. The wasps lay eggs on the hornworm and once they hatch they’ll feed on the hornworm until they are ready to pupate. Let this hornworm be because next year you will have even more braconid wasps to help you. Other ways to take care of hornworms include using Monterey Garden Insect Spray, Green Light Lawn & Garden Spray, or Dipel Dust on your plants- all products we carry here at Farmer D Organics.
I hope that this helps all of you gardeners to grow great veggies!! Until next time, don’t get too pestered!