The taxonomic scheme classifying the butterflies and moths is as follows (Mendoza, 2001):

    Kingdom Animalia
       Phylum Arthropoda
          Subphylum Uniramia
             Class Insecta
                Subclass Pterygota
                   Infraclass Neoptera
                       Order Lepidoptera

There are no known lepidopteran studies done in the Diliman area but the list of extant Philippine species is quite extensive (Baltazar, 1990). However, previous studies on lepidopteran diversity have been performed within the nearby environs of UP – Diliman. A survey conducted in Tanay area, Rizal province from 1989 to 1996 demonstrated a high species diversity per unit area. Eighty – five species from 12 lepidopteran families Amathusidae, Danaidae, Hesperiidae, Lycaenidae, Nemeobidae, Nymphalidae, Papilionidae, Pieridae, Pyralidae, Satyridae, Saturnidae, and Sphingiidae were collected from 4 sampling sites in the said area (Sundholm, 1998).

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The distinguishing characteristics often used in lepidopteran classification are the venation and shape of the wings (see picture). Wings may either be homoneurous where the venation of the forewings and hindwings alike or heteroneurous where forewings and hindwings different. With respect to surface texture, wings can be characterized as aculeate where specialized bristles cover the wings or nonaculeate if there is absence or sparseness thereof. Extensive branching is correlated with primitiveness, while reduction in veins is considered to be an advanced trait (CESA, 1998).

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Lepidopterans develop through a four-stage metamorphosis: embryonic (egg), the nutritive stage (larva), the transition stage (pupa or chrysalis), and the reproductive and dispersive stage (adult or imago) (see picture). Minute and resistant eggs are produced in large quantities and mostly laid on shady, vegetation - rich environments. The larval lepidopteran, the caterpillar, develops inside the egg, and is released by consuming its encasement. By substrate feeding, the caterpillar consumes foliage until a considerable increase in size is achieved. Subsequently, the larva enters an immobile state, the pupal stage. In moths, the pupa is enclosed in a glabrous covering, the cocoon, which the larva spins. Some larvae enter the pupal stage even without an encasement. During this period, the larval structures transform to those of the adults. The fully formed adult lepidopteran breaks out of its encasement (Klots, 1991).

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The larvae of the butterfly and the moth are of the greatest concern to man due to their economic and ecological importance. In the textile industry, the silkworm moth Bombyx mori has been utilized as a source of commercial silk. The silkworm larva subsists exclusively on mulberry Morus leaves. It spins layers of double filaments of silk around its body as it prepares to enter the chrysalis stage. The silk is harvested through a series of processes known as sericulture. The Philippine fibercrop industry is basically composed of the cotton, abaca, and silk industries. However, the dearth in information regarding silk production in the country reflects the rapid deterioration of the industry. In 1997, a total of 0.2 metric tonnes of cocoon was harvested in the country, representing a small percentage of the world cocoon production (Ranola, 2001). Worldwide production of silk reached 50,000 metric tonnes in 1985 (History, N. d.). At the same time, butterflies and moths are important pollinators, in effect, of agricultural and horticultural value. However, industrial scale utilization of butterflies as pollinators is not documented.

Similarly, lepidopterans can also cause severe ecological and economic damage if their numbers are left unchecked. Most moth species feed on plants and other resources that are valuable to man. In the 1970s, a massive reforestation program undertaken by the Philippine government was sabotaged by the attack of stem borer Hypsipyla robusta Moore (Lepidoptera: Cossidae) on young trees. This stem borer species specifically targets the mahogany tree Swietena macrophylla. Its economic impact on the logging industry has not yet been assessed, however, losses on the reforestation program runs at about US$ 50,000 per 100 hectares of damaged S. macrophylla plantations (Lapis, 1997).

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Butterflies, like birds, are widely considered to be good indicators of environmental changes. In addition, data collection is much easier by using these organisms compared to other organisms such as beetles, spiders and molluscs (Harding et al., 1995). When changes in the population size or distribution of butterflies take place, corresponding disturbances in the environment may have occurred. Rapid degradation of traditional lepidopteran habitats at the Neotropics forces migration or adaptation. Plants utilized by butterflies for foraging are depleted due to wilting, or to some extent, desertification. Butterflies respond by migrating to higher elevations or latitudes, or adjusting the length of their larval stages (Parmesan, 1996). Lepidopteran migration also signals the arrival of their traditional predators and an impending scarcity on food supplies.

Lepidopteran surveys provide pertinent data with relation to spatial and temporal conditions, weather, terrain, and vegetation. It has been shown that index values for butterfly populations increase when the weather prior to and including flight period is warm and dry. On the other hand, when faced with high temperatures and winds, butterfly counts maybe depressed. When hot, these insects cool down under shades provided by vegetation or topographical features. Also, flight in some lepidopteran species only occurs under the presence of sunlight. Abundant data have been obtained from surveys made under the sun and shade (Pollard and Yates, 1993). On the other hand, migration of butterflies is a response to seasonal weather patterns. A study on lepidopteran behavior in the Kwale District in Kenya shows that the northward migration of butterflies suggests the onset of the rainy season (Mwadime, 1996).

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