'/9 -k -~ 1 -, ?$ A N P V-I . J q~ -- 2 K C 1 y 1 ~I "',~j$2 Photo 2 -Sycamore leaf beetle adults. Photo 3 -A typical egg case. The case is only about 1.5 mm long; at first glance it may appear to be only a brown fleck on the leaf. i; t~ P Photo 4 -Late-stage larvae with cases. Leaf pubes- cence on cases provides some camouflage for larvae (See Photos 8 and 9) THE SYCAMORE LEAF BEETLE 7 Photo 5 -Clockwise from top left: Completed larval case (the pupal case ); and prepupa, pupa, and newly formed adult with case removed. 4 Photo 6 -Ovipositing females engaged in construction ol the egg ca.. t is greenish while being formed but soon hardens and turns brown. Each case is attached to the leaf by a short stalk. Photo 7 -Early stage larvae and cases. The egg case serves as the beginning of the larval case. Cases are enlarged as larvae grow, and in late-stage larvae, the egg case becomes the tip. ALABAMA AGRICULTURAL EXPERIMENT STATION J r% alBO -&a ii, L4J) k>l "r t v iB 41 t r Photo 8 -Late-stage larvae as commonly seen feeding or resting on the under surface of sycamore leaves. Larvae with cases coated with pubescence may Photo 9 -Late-stage larvae resting on a sycamore twig. On twigs larval cases sometimes resemble buds. 1V atace to meia npeaion 'g~or up Photo 10 -Full-grown larval case sealed and2 attached to the leaf in preparaton for pupation. Inset - typical dead spot on the opposite surface of the leaf at the point of case attachment. Photo I I -New-brood adult and basal section of the case from which it emerged. THE SYCAMORE LEAF BEETLE 9 turbed. However, egg-laying females usually remained in place, affording the opportunity to witness the process of oviposition and case construction. The process was as described by Karren (3) for the Chlamisinae in general. The egg was attached to the leaf surface by a short stalk, then enclosed in a case made by depositing bits of fecal material around the egg (Photo 6). In this process, the case was rotated with the hind legs, thus the attaching stalk was twisted. When the egg was completely encircled, the case was then capped across the top. The entire process usually required 15-20 minutes. The primary egg-laying period extended to about the first week of June, but some oviposition was witnessed in mid-and late June. In the field, egg hatch and larval activity began each year in April (April 12, 16, 18, 29 in 1991, 92, 94, and 93, respectively) 8 to 15 days after eggs were first found (see graph). In the laboratory, eggs hatched in 8 to 11 days. Newly hatched larvae did not completely exit the egg case; the case was carried along and served as the starter for the larval case (Photo 7). Larvae hatching from eggs laid on the upper surface of leaves generally moved promptly to the lower surface. Larvae fed primarily on the lower surface on tissue between leaf veins (Photo 8). As larvae grew, they enlarged cases by adding fecal material to the egg case. By the end of May, larvae of all sizes, newly hatched to fully grown, could be found on infested trees. The usual number of larvae per leaf was one (on 185 of 200 leaves examined), but occasionally two to five. Larvae were present into the last half of August. They were found primarily on the underside of leaves, but occasionally were observed on the upper surface (Photo 4) and on small twigs (Photo 9). Larval cases on twigs resemble buds and may be easily overlooked. Pupation began in the field in late May (1991) and early June (1992, 93), 37 to 47 days after egg hatch was first observed (see graph). In the laboratory, larvae completed development and pupated in 25 to 36 days (average of 30 days for 17 larvae). The pupation process followed that outlined by LeSage (4) as common among most species of Neochlamisus. The full-grown larva ceased feeding, and sealed and attached the base of the larval case to the host plant; sealed cases were commonly found on the lower surface of the leaf (Photo 10). Leaf tissue at the point of attachment died, leaving a small, circular brown spot visible on the opposite surface (Photo 10). Prior to pupating, mature larvae apparently reversed position from that of feeding to face the apex of the case. In each of more than 30 fixed cases examined, the head of the form present (prepupa, pupa, or new adult) faced the apical end of the case. Emergence of new-brood adults began in the field mainly in early July, 2729 days after start of pupation (see graph); however in 1991, some scattered emergence was noted as early as June 17. In the laboratory, new adults emerged in 17- 10 ALABAMA AGRICULTURAL EXPERIMENT STATION 91 949293 " . 91 9293 *o * 94 9192 93 o. 94 91 94 .·. 91 I Overwintered Adults 92 I Eggs 91 o Larvae 92 93 93 92 . "Pupae 93 91 92 * I I New-brood Adults I I I 939294 . . . I I I April May June July August September October Figure I -Seasonal cycle of the sycamore leaf beetle in east-central Alabama, 1991-94. Solid black dots at beginning of each life-stage bar signify the onset of that stage in each corresponding year indicated. Dots at the end of bars designate as follows: Overwintered parent adults - last dates oviposition was witnessed; Larvae - last dates active larvae were observed; New-brood adults - last dates adults were observed in the field. New-brood adults hibernate through winter, thus are inactive from SeptemberlOctober until April. 22 days. In the process of emerging, the adult cut through the case at a point about one-half to two-thirds the length from the base and exited from the open apical end; the basal section of the case remained sealed to the leaf (Photo 11). Empty cases were the primary indicator of presence of new adults. New-brood adults were observed to feed on tissue between leaf veins (Photo 11), and often were found resting on the underside of the leaf at junctures of midrib and veins. Adults were observed on foliage until September 2, 9, and 21 in 1993, 92, and 94, respectively, and until October 20 in 1991. The time that adults moved from trees into hibernation in the field appeared to be influenced by the availability of foliage suitable for food. In the laboratory, several new-brood adults fed and lived for four to six months when supplied regularly with green sycamore foliage. In the field, the period of activity of the overwintered parent adults appeared to overlap the start of emergence of new-brood adults. In years when the beetle was abundant, adults could usually be found fairly regularly, and there seemed to be no THE SYCAMORE LEAF BEETLE II well-defined, extended period of adult absence to mark the end of the parent brood and beginning of the new. The primary egg-laying period ended in about the first week of June, but some scattered oviposition was witnessed to the end of June. Empty pupal cases noted on foliage in late June - early July indicated that newbrood adults were present; however, no corresponding renewal of oviposition was observed. Therefore, it appears that egg-laying witnessed in late June was by laggard overwintered adults, and probably marked the end of parent adult activity. New adults apparently did not mate and oviposit, but overwintered in hibernation and laid eggs the following spring. Thompson and Solomon (5) reported the possibility of two broods of N. platani in the Mississippi Delta. However, according to Karren (3), North American species of Chlamisinae apparently produce only one larval brood each year. From evidence obtained in this study, it appears that in Alabama only one generation of sycamore leaf beetle occurs each year. DAMAGE AND IMPORTANCE Historically, occurrence of the sycamore leaf beetle in mixed natural forest stands in Alabama has gone unnoticed. However, on shade and ornamental sycamore the beetle is sometimes a serious pest. Both adults and larvae feed on leaves, but it is the larval stage that consumes the most foliage. Theoretically, heavy infestations could destroy sufficient foliage to reduce tree vitality and contribute to loss in growth or dieback in crowns; however, healthy trees usually recover without serious permanent injury. The most common and serious damage attributed to the sycamore leaf beetle is the destruction of the aesthetic value of ornamental trees. Larvae seem to prefer to feed on young leaves. These leaves are generally found at the end of branches in the periphery of the crown, thus feeding damage is highly conspicuous. Light infestations of sycamore leaf beetle do not usually warrant control. Heavy infestations, particularly on young trees with limited foliage, may so mar crowns that control may be desirable. For recommendations on control of sycamore leaf beetle on shade and ornamental trees, contact the County Extension Office or appropriate extension personnel. SUMMARY The sycamore leaf beetle is a pest of shade and ornamental sycamore trees. Adults and larvae feed on foliage. Heavy feeding results in unsightly crowns and reduces the aesthetic value of trees. In east-central Alabama, hibernating adults emerged during the first half of April. Adult feeding and oviposition began promptly. The primary egg-laying period was 12 ALABAMA AGRICULTURAL EXPERIMENT STATION April, May, and the first week of June, but some oviposition continued until the end of June. Eggs were laid singly on both upper and lower surfaces of leaves. Each egg was enclosed in a small, brown, bell-shaped case made of fecal material secreted by the female. Egg and case were attached to the leaf by a short stalk. In the field, eggs hatched in 8-15 days, with hatch beginning in the last half of April. Larvae fed on the underside of leaves for 37-47 days (in the laboratory, larvae completed development in about 30 days), and were present in the field until late August. Larvae fed and developed in a case made by adding fecal material to the egg case. The completed larval case was brown and cone-shaped, 3-3.5 mm in diameter at the base and 7-8 mm long. Pupation occurred in the finished larval case sealed at the base to the leaf. New-brood adults emerged in 27-29 days (18-22 days in the laboratory), with emergence in the field beginning in late June - early July. Adults were present into September and October. New-brood adults apparently did not oviposit following emergence, but overwintered and laid eggs in the following spring. Thus, it appears that only one generation occurred each year. The sycamore leaf beetle is an important pest because of damage caused to foliage of shade and ornamental sycamore. Feeding by heavy infestations can destroy much of the foliage in the periphery of crowns. Healthy trees usually survive and recover, and from this standpoint, control of the beetle is not usually necessary. However, when damage is severe, control to preserve the ornamental value of trees may be desirable. For control recommendations, contact the County Extension Office or appropriate extension personnel. REFERENCES (1) Balsbaugh, Jr., E.U. and K.L. Hays. 1972. The leaf beetles of Alabama (Coleoptera: Chrysomelidae). Ala. Agric. Exp. Stn. Bull. 441, 223 pp. (2) Harlow, W.M. and E.S. Harrar. 1969. Textbook of Dendrology. McGraw-Hill Book Co. New York. (3) Karren, J.B. 1972. A revision of the subfamily Chlamisinae of America North of Mexico (Coleoptera: Chrysomelidae). Univ. Of Kansas Sci. Bull. XLIX, No. 12:875-988. (4) LeSage, L. 1984. Immature stages of Canadian Neochlamisus Karren (Coleoptera: Chrysomelidae). Can. Entomol. 116:383-409. (5) Thompson, L.C. and J.D. Solomon. 1986. Insect defoliators sycamore plantations. Ark. Agric. Exp. Stn. Bull. 897, 24 pp. of young