Leaffooted Bug
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LEAFFOOTED BUG Integrated Pest Management for Landscape Professionals and Home Gardeners Leaffooted bugs are medium to large sized insects that feed on fruits, fruiting vegetables, nuts, and ornamentals. They have piercing-sucking mouthparts that allow them to feed on plant parts, par- ticularly seeds. Leaffooted bugs are in the family Coreidae and get their name from the small leaf-like enlargements found on the hind leg. They are closely related to other sucking insects, such as stink bugs (family Pentatomidae) that Figure 1. Leptoglossus zonatus adult. Figure 2. Leptoglossus clypealis adult. can also suck juices from plants. The two yellow spots on the pronotum The sharply pointed, thornlike clypeus behind the head are characteristic of at the tip of the head is characteristic of IDENTIFICATION this species. (D. Haviland, UCCE Kern Co.) this species. (J.K. Clark) There are three common species of leaf- footed bugs that are native to California and the western United States. These include Leptoglossus zonatus, L. clypealis, and L. occidentalis (Figures 1-3). Adults of all three species are about 0.75 to 1 inch long and have a narrow brown body. Adults of all three species are similar in appearance, except that: • L. zonatus has two yellow spots just behind the head (on the pronotum) Figure 3. Leptoglossus occidentalis Figure 4. Leaffooted bug eggs are laid (Figure 1). adult. (L.L. Strand) end to end in one or more strands. • L. clypealis has a thorn-like projec- Holes in these eggs on a pistachio tion called a clypeus that extends hull indicate that larvae have already hatched. (D. Haviland, UCCE Kern Co.) forward from the tip of the head (Figure 2). • L. occidentalis has neither of these features (Figure 3). All three species have a white zigzag pattern across the wings: this pattern is prominent in L. zonatus and L. clypealis and is relatively faint in L. occidentalis. The brown, cylindrical eggs of all three species are laid end-to-end in a string- like strand on the host plant, often along Figure 5. Leaffooted bug nymph. Figure 6. Nymphs of assassin bugs, a stem or leaf midrib (Figure 4). Most (D. Haviland, UCCE Kern Co.) which are beneficial predators, resemble egg masses have 10-15 eggs, though leaffooted bug nymphs but are lighter colored. (J.K. Clark) more than 50 have been reported. Eggs hatch into small nymphs that have dark heads and dark legs on bodies that sassin bug (Zelus renardii) (Figure 6). Nymphs of this beneficial insect have light-col- range in color from orange to reddish- ored legs and antennae and hatch from barrel-shaped eggs that are grouped together brown (Figure 5). Small leaffooted bugs with a white cone top. As leaffooted bug nymphs become larger, they can easily be can be confused with nymphs of the as- recognized by the development of the leaf-like projection on the hind legs (Figure 5). PEST NOTES Publication 74168 Statewide Integrated Pest Management Program May 2014 May 2014 Leaffooted Bug LIFE CYCLE gardeners as a pest of tomatoes (Figure 8) and pomegranates (Figure 7); farm- Leaffooted bugs overwinter as adults, ers primarily report it as a pest of al- typically in aggregations located in monds, pistachios, and pomegranates. protected areas, such as in woodpiles, Other important hosts in California barns or other buildings, palm fronds, include young citrus fruit, cotton bolls, citrus or juniper trees, under peeling watermelons, and several ornamental bark, or in tree cracks. Cold winters kill trees and shrubs. L. clypealis also has a many adults, and major outbreaks often wide host range within gardens, land- occur after mild winters. Overwintered scapes, and farms and is the predomi- adults live from September/October nant species found on desert plants like until late spring. When weather gets palm trees, Joshua trees, and yucca. L. warm, typically in March in the San Figure 7. Aggregations of L. zonatus on occidentalis, also known as the western Joaquin Valley and April in the Sacra- pomegranate fruit. conifer seed bug, is primarily found in (D. Haviland, UCCE Kern Co.) mento Valley, adults disperse to find association with conifer trees. food sources. Adults are strong flyers that may feed initially on the seeds of winter weeds and later move into gar- DAMAGE dens, landscapes, and farms in search Leaffooted bugs have piercing-sucking of early-season fruit and a place to lay mouthparts that extend more than half eggs. of the length of the narrow body. They use this mouthpart to probe into leaves, Overwintering leaffooted bugs can shoots, and fruit to suck plant juices. lay over 200 eggs during a two-month The depth of the probing depends on period in the spring. Nymphs emerge the size of the bug: small nymphs feed from the eggs about 1 week after being shallowly on superficial plant juices, deposited, after which they develop whereas adult bugs probe deep into into adults in 5 to 8 weeks. Adults are fruit in search of seeds. If a hard seed is Figure 8. Leaffooted bug nymphs on long-lived and can lay eggs over an found, such as an almond kernel or ju- tomato. (R. Ostroff) extended period, so the population can niper berry, the bug excretes digestive consist of all life stages by late June. At enzymes from its mouthparts to liquefy this time, overwintering adults are still a small part of the seed so that it can be alive as the first generation of their off- ingested. Leaffooted bug mouthparts spring develop into adults. During the are also known to carry a fungal yeast, spring and summer, there are typically Eremothecium coryli (formerly known two to three generations of leaffooted as Nematospora). When leaffooted bugs bugs. In the fall, all bugs develop until feed, this yeast can be introduced into they become adults that overwinter in fruit causing a variety of symptoms aggregations (Figure 7). usually related to discoloration. How- ever, the yeast causes no damage that Population levels change from year to would limit the ability of the fruit to be year depending on weather and para- harvested and consumed. This infec- sitism of eggs. Populations are typically tion is most predominant when rains highest after mild winters that allow are abundant. Figure 9. Leaffooted bug excrement on the surface of a pomegranate fruit. high survival of overwintering adults. (D. Haviland, UCCE Kern Co. ) Seasonal fluctuations in the number For most ornamental and many garden of bugs can also be related to rainfall, plants, feeding on the leaves and shoots food availability, and the prevalence of causes no visual damage and is of little spores gain entry into the fruit through natural enemies. concern. The most destructive damage the feeding wound. Large aggregations occurs when bugs feed on fruit. Early- of leaffooted bugs can also leave excre- Host Plants. In the spring, leaffooted season feeding on nuts like almonds bugs often feed on thistles and other and pistachios can cause the kernel to ment on the surface of the fruit that can weeds. Adults migrate from weedy abort and die, and mid- to late-season reduce its aesthetic appeal (Figure 9). areas into gardens and landscapes, feeding on nuts causes a black stain Feeding on small fruit (e.g., tomatoes) particularly when fruits have started on the kernel. On pomegranates, late- can cause the fruit to abort, while feed- to ripen. L. zonatus is the most de- season feeding as the fruit ripens gen- ing on medium-sized fruit can result structive of the leaffooted bug spe- erally causes no external damage but in depressions or discoloration at the cies. It feeds on many types of plants can cause aryls (seed-like structures) to feeding site as the fruit expands and a n d i s m o s t c o m m o n l y r e p o r t e d b y darken and wither, especially if fungal ripens. Feeding on mature tomatoes ◆ 2 of 4 ◆ May 2014 Leaffooted Bug can cause slight discoloration to the layers or fruit clusters, and they may surface of the fruit that should be of no hide or fly when startled. Handpick and concern to backyard gardeners. crush the bugs or brush them off plants into soapy water. Wear gloves because MANAGEMENT of the odor they will emit when han- During most years, leaffooted bug dled. A handheld vacuum dedicated populations are low enough that dam- to catching the bugs can be effective age to gardens is tolerable and damage at reducing numbers, if used regularly. to landscape plants is negligible. When It is especially important to remove outbreaks occur, a variety of methods the bugs as early in the season as pos- will likely be needed to manage this sible, when the very young nymphs are pest, which may include removing tightly clustered together, and morning Figure 10. The parasitoid Gryon pennsyl- overwintering sites or the use of weed is best to reduce movement and flight. vanicum lays its eggs inside of the eggs host removal, row covers, physical Be sure to also destroy the egg masses of leaffooted bug. Parasitoid eggs hatch removal, natural enemies, and insec- found on the underside of leaves. into larvae that develop into adults ticides. Achieving good control will within the leaffooted bug egg. likely require some combination of For late-season infestations in pome- (D. Haviland, UCCE Kern Co. ) these methods. granate trees, prune trees so that there is a space between tree limbs and the Insecticides. Insecticides are rarely Remove Overwintering Sites. Adult ground. Leaffooted bug nymphs can bugs overwinter in woodpiles, under needed for leaffooted bug control be- easily be knocked out of the tree using the bark of eucalyptus, juniper, or cause small blemishes on most fruit are a stick, by physically shaking the tree cypress, and in outbuildings.