Insects of summer
There have been a variety of unfamiliar insects that have been conspicuous in the landscape recently. When you don't recognize an insect, you wonder whether to treat it as a pest. However, once an insect in identified and its biology learned, it is easier to understand its role in your garden and landscape. Although many of the following insects have been accused of damaging plants, they are not considered to be pests.
Cicadas are present from mid to late summer, although they are more often heard than seen. They produce a high-pitched sound during the day that resembles a powerline hum. Cicadas have a stout, one inch long body. They have conspicuous, clear wings which are folded over their back. Cicadas have been occasionally described as beetles with wings sticking out. Sometimes people describe the nymphs as ‘beetles that turn into flies'. Cicadas are actually more closely related to leafhoppers, planthoppers, and spittlebugs.
The immature nymphs live in the soil feeding on the roots of various plants, especially perennials. When the nymphs are in their last development stage, they emerge from the soil, attache themselves to an object, like a tree trunk or fence post, and molt into adults. Despite their size, cicadas are harmless to people and garden plants. Cicadas can, however, potentially injure trees when they use their sharp ovipositor to lay eggs in twigs.
Katydids are green and about 1 ½ inches long (not including the antennae). They have enlarged back legs (for jumping), long antennae (about the length of their body), and are grasshopper-like. Like grasshoppers, they possess chewing mouthparts.
Katydids are normally found in trees and shrubs where they feed on foliage, although they are not known to injure woody plants. They may also be found resting on herbaceous plants. Although katydids can potentially feed on garden plants, any injury is probably minor. If there is a lot of feeding, check instead for pests like variegated cutworms or slugs. It should not be necessary to control katydids to protect your plants.
Katydids are also known for their “singing.” Their distinctive sound is produced at night by males to attract a mate. They rub their wings together, resulting is a rapid pulsed sound that can be repeated over and over. This singing can continue for most of a night and can occur for several consecutive nights or in some cases, for weeks. There is no practical control for katydids, especially when they are in trees. It is best to tolerate them and wait until they finish on their own.
Soldier beetles are very common on flowers from mid to late summer. They readily fly and can resemble wasps when in flight. They are about ½ inch long, yellowish to tannish brown with soft wing covers. There is a black spot on each wing cover. Like other beetles, soldier beetles have chewing mouthparts. They are closely related to fireflies but lack the light-producing organs that fireflies possess.
As larvae, soldier beetles are predaceous on other insects. Not much is known about the adults, although they apparently are also predaceous on other insects. Despite the large numbers that may be noticed in gardens, they do not damage flowers or other plants. It is not necessary to control them, just ignore them. Read more about soldier beetles.
Scarab beetles are a common, diverse group of beetles. There have been a couple large-sized scarab beetles that have been noticed in the landscape recently. Grape pelidnotas, Pelidnota punctata, are tan to reddish brown in color with three black spots on each wing cover. They are about one inch long, oval, and robust. They look similar to June beetles, although they are more closely related to Japanese beetles. Also known as spotted grapevine beetles, they feed primarily on grape leaves. Fortunately, their feeding is not serious and control is usually not necessary.
Another scarab beetle that may be observed is a type of flower beetle, Osmoderma eremicola. Sometimes known as the hermit flower beetle, this beetle is about one inch long and is dark brown to black. It is somewhat similar to June beetles but is not quite as oval. The larvae feed in decaying wood and the adults are associated with loose bark and tree cavities. They are not a pest of trees and do not need to be controlled.
Sphecid wasps are a type of solitary wasp. They are known to nest in soil, in plant stems, or in cavities in buildings. Although they live by themselves, they can live gregariously, i.e. other sphecid wasps of the same species may nest nearby. Sometimes many individuals are present (Note: You can distinguish between ground-nesting sphecid wasps and ground-nesting yellowjackets by observing how many nest openings there are. A yellowjacket nest will have many different individuals entering and leaving a single nest opening while there will be more than one nest opening (sometimes many) for sphecid wasps.
Sphecids prey on other insects which they feed to their young. They sometimes can be observed carrying insects back to their nest. Although sphecids may sting to protect themselves, they are nonaggressive towards people and the incidence of stings is very, very low. Sphecid wasps rarely need to be controlled because if the risk of stings.
Cicada killers, Sphecius speciousus, are a striking black and yellow patterned sphecid. They are very large, 1 - 1 ½ inches long and nest in the soil. Like their name suggests they often prey primarily on cicadas. Despite their size, there is little concern for stings. The males are not able to sting and although females can sting, they are very unaggressive.
People may also see Sphex pensylvanicus, a 1 - 1 1/4 inch long black sphecid. The wings are a smoky black with a violet iridescence. They also capture large-sized insects, such as katydids and nest in the ground. This wasp has been occasionally seen visiting flowers. Although it's just feeding on nectar, it has been accused of injuring plants. However, they do not harm plants, and any damage seen where this sphecid is present is coincidental. Sphecid wasps do not need to be controlled to protect plants.
Published in Yard & Garden Line News, August 15, 2001