Distribution. Several species of Leptoglossus affect crops; L. phyllopus (L.), L. oppositus (Say), and L. clypea-lis Heidemann are most common as vegetable pests. L. phyllopus is common in the southeastern states, extending north to New York and west to Missouri. L. oppositus occurs throughout the eastern United States, extending as far west as Minnesota and Arizona. L. cly-pealis is found from the Midwest to the Pacific Coast states (Slater and Baranowski, 1978). A related bug, Phythia picta (Drury), occasionally is found feeding on cucurbits and some other vegetables in California, Florida, and Texas (Baranowski and Slater, 1986).
Host Plants. Although commonly associated with squash and cantaloupe, Leptoglossus spp. feed on a variety of crops, including artichoke, bean, cucumber, pea, potato, southern pea, tomato, and watermelon. Field and fruit crops, particularly soybean and orange, also are damaged. These bugs are sometimes found feeding on weeds, and L. phyllopus was reported by several authors to have a strong preference for thistles. A list of occasional weed and crop hosts was given by Baranowski and Slater (1986).
Natural Enemies. Arnaud (1978) reported that Leptoglossus spp. were parasitized by the tachinids Trichopoda pennipes (Fabricius), T. plumipes (Fabricius), and Trichopoda sp. (all Diptera: Tachinidae).
Life Cycle and Description. The biologies of these insects have not been thoroughly studied. Only one generation per year is known. Apparently they overwinter as adults, emerging to feed on weed hosts in late spring.
Leaffooted bugs deposit rows of gold, bronze, or brown eggs, laid end to end on foliage or stem tissue, usually along a vein or stem. The length of an individual egg is about 1.4 mm, and the width about 1.01.15 mm. The eggs hatch in 5-7 days. The orange, red, or reddish-brown nymphs have 5 nymphal instars; 2530 days is usually required for maturity.
The leaffooted bugs get their name from the peculiar flattening of the hind tibia, which resembles a leaf. They are usually about 20 mm long, and brown in color. L. phyllopus bears a fairly uniform, broad white band across the wing covers. L. oppositus, in contrast, lacks a white band, though small white spots may be present on some individuals. L. clypealis has a white band on the wing covers, but its pattern is jagged. The latter species is also distinguished by having a pronounced spine projecting forward from the head.
The biological information on leaf-footed bugs was provided by Chittenden (1899a, 1902), and a good description of L. oppositus nymphs by Chittenden (1902).
Leptoglossus spp. feed on foliar tissue and fruit. They may cause wilting and death of leaves, and deformities of fruit. Apparently only adult L. phyllopus affect
vegetables, with the immatures developing on thistle. With L. oppositus, however, nymphs are found on vegetable plants and this insect behaves much like squash bug, Anasa tristis; groups of insects of all stages aggregate on sheltered areas of the host plant. Chittenden (1902) reported that a toxic feeding secretion was produced by L. oppositus. A study in South Carolina compared the damage to southern peas by L. phyllopus and southern green stink bug, Nezara viri-dula, and found that three L. phyllopus per plant during early bloom stage could cause 54% total yield loss (Schalk and Fery, 1982). Late-bloom infestations, in contrast, caused only a 22% yield reduction. Stink bug feeding was more damaging, even with equivalent insect population densities, causing 100% and 74% yield loss at these two plant growth stages, respectively. (See color figures 136 and 137).
Insecticides. Leptoglossus spp. are not difficult to control with insecticides. They most often cause injury when adults disperse into a susceptible crop, usually one with small fruit, where insecticides were not applied.
Cultural Practices. Because L. phyllopus breeds on thistle and other weeds, weed management has been suggested as an important factor in minimizing damage potential. The young of L. oppositus, however, are often found attacking tree fruit early in the season (Chittenden, 1902).
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