|Crop Knowledge Master|
Thrips hawaiiensis (Morgan)
|Hawaiian Flower Thrips|
Ronald F.L. Mau, Extension Entomologist
Jayma L. Martin, Educcational Specialist
Department of Entomology
This thrips occurs in large colonies in flowers of many plants, and has a preference for plants belonging to the Leguminosae and Convolvulaceae families. It is considered a minor pest of beans (Kono and Papp, 1977). Other plant hosts include Acacia confusa, Acacia farnesiana, Acacia koa, alfalfa, asparagus, Astelia menziesiana, aster, avocado, banana, Batis marinima, beach naupaka, bell pepper, coffee, guava, Hibiscus, kukui flowers, mangoes, orchids, pakalana, peppers, pikake, plumeria, prickly poppy, radish, rose and all squashes. An extensive list of hosts recorded in Hawaii is presented by Zimmerman (1948).
This is a widespread species in tropical and temperate climates. Some countries that it is present in are Angola, Bangladesh, China, Formosa, Indonesia, Japan, Laos, Malaysia, Mozambique, New Guinea, Nigeria, Norfolk Is., Pakistan, Sierra Leone, Sri Lanka, Tahiti, Thailand and Uganda (Sen et al., 1988). It is present on all major Hawaiian islands except Lanai.
Thrips puncture the leaves, flowers, or stems with their mouth parts and suck up the exuding sap. The Hawaiian flower thrips feeds only on flowers of hosts (Takahashi, 1936). Depending on the extent of feeding, flowers become flecked, spotted, or deformed.
The life cycle of this thrips has not been determined. However, the development of the pest is similar to that of other thrips species. The descriptions given below for the immature stages (eggs, larvae and pupae) are based on life history information for thrips given by Lewis (1973).
Thrips have 5 developmental stages (instars), the egg, 2 feeding stages, 2 non-feeding stages, and the adult. The feeding instars (the first 2 stages) are called larvae and the non-feeding instars are called pupae. Durations of each stage vary depending on species, host, and temperature. Many thrips species are bisexual and eggs are laid after copulation, but in many species males are rare and females have the ability to reproduce without fertilization (parthenogenetically). Most thrips lay eggs, but some species can birth live young. The Hawaii flower thrips lay eggs. Generations are continuous in Hawaii.
Eggs are kidney shaped. The egg shell is smooth, delicate, and pale white or yellow in color. Eggs are very small, measuring less than 22/1000 inch (550 µ) long by 10/1000 inch (250 µ) wide. They are usually laid singly in a scattered pattern, but sometimes may occur in rows alongside or beneath veins. They are partially or completely inserted into an incision made into the plant tissue by the saw-like ovipositor of the female (Lewis, 1973). Eggs hatch in 3 to 6 days, but may take as long as 20 days (Ananthakrishnan, 1984).
The first instar larvae are white or nearly transparent at first. Their small bodies consist of the head, 3 thoracic segments and 11 abdominal segments, 3 pairs of similarly structured legs and no wing buds. The duration of the first instar is about 1 to 5 days. When the first instars have doubled in size they find a protected spot and molt. The second instar larvae are white to yellow white, and have antennae that are shaped differently (Lewis, 1973).
When the second instar larvae are ready to molt into the pupal stage they usually move into the soil or litter beneath the host plant. We believe that the Hawaiian flower thrips behave in this manner. Whether it then molds a simple earthen shell lined with thin silken web (Lewis, 1973) as in other thrips species is unknown. The duration of the larval stage is between 4 to 10 days (Ananthakrishnan, 1984).
The first instars of the pupal stage are called prepupae and represent an intermediate stage between the larvae and true pupae. These individuals have wing buds (an early stage of wing development), rudimentary antennae, and do not feed or excrete. A single pupal stage follows after a molt. Pupae have developed antennae that curve back over the head. The wing pads have developed into long sheaths, and the legs and bodies have assumed adult proportions (Lewis, 1973). The entire pupal stage requires 3 to 10 days (Ananthakrishnan, 1984).
This thrips has a dark brown body, yellow legs, and brown antennae except for segments III and the base of segments IV and V which are yellow. Adults have two pairs of very slender wings fringed with long hairs that lay longitudinally over the back when not in use. The forewings are grayish-brown with a clear base. Females are about 3/50 inch (1.5 mm) long and the males are slightly smaller (Kono and Papp, 1977). Males are as common as females (Takahashi, 1936). The head is about as long as it is wide. The taxonomic classification of this species has been confusing because some individuals within a population can have seven antennal segments while others have eight (Zimmerman, 1948).
Unlike other flower thrips, this species prefers wet and shady areas (Sakimura and Krauss, 1944).
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No information available.
Ananthakrishnan, T.N. 1984. Bioecology of Thrips. Indira Publishing House: Oak Park, Michigan. 233 pages.
Bhatti, J.S. 1980. Species of the Genus Thrips from India (Thysanoptera). Syst. Ent. 5: 109-166.
Kono, T. and C.S. Papp. 1977. Taeniothrips hawaiiensis (Morgan). pp. 124-126. In: Handbook of Agricultural Pests. Department of Food and Agriculture Division of Plant Industry Laboratory Services - Entomology. 205 pages.
Lewis, T. 1973. Thrips Their Biology, Ecology and Economic Importance. Academic Press: London, New York. 349 pages.
Palmer, J.M., L.A. Mound, and G.J. duHeaume. 1989. Cie Guide to Insects of Importance to Man 2. Thysanoptera (C.R. Betts ed.). CAB International Institute of Entomology, British Museum of Natural History. 73 pages.
Sakimura, K. and N.L.H. Krauss. 1944. Thrips from Maui and Molokai. Proc. Hawaiian Entomol. Soc. 12(1): 113-122.
Sakimura, K. and T. Nishida. 1944. Thrips from Kauai. Proc. Hawaiian Entomol. Soc. 12(1): 123-133.
Sen, S., N.K. Pramanik and C.K. Sen Gupta. 1988. Thrips hawaiiensis (Morgan). pp. 21. In: Thysanoptera Fauna of North-Eastern India. Records of the Zoological Survey of India. 123 pages.
Takahashi, R. 1936. Thysanoptera of Formosa. Philippine J. Sci. 60: 427-458.
Zimmerman, E.C. 1948. Taeniothrips hawaiiensis (Morgan). pp. 415-417. In: Insects of Hawaii Volume 2 Apterygota to Thysanoptera. University of Hawaii Press, Honolulu. 475 pages.