576 AN INTRODUCTION TO ENTOMOLOGY 



reduced to mere vestiges. Wheii only one pair of palpi are developed 



they are the labial palpi; 

 when maxillary palpi are 

 present they can be dis- 

 tinguished by their at- 

 tachment to the maxillae. 

 If the head of a but- 

 terfly or of a moth in 

 which the mouth-parts 

 are not vestigial be ex- 



„. „ r. .. t .„ amined, there will be 



Fig. 714. — Cross-section of maxillae. x j 1 1 • 



found a long suckmg- 



tube which when not in use is coiled on the lower side of the head be- 

 tween two forward-projecting appendages. This long sucking-tube is 

 composed of the two maxillae, greatly elongated, and fastened to- 

 gether side by side. In Figure 713 there is represented a side view of 

 the maxilla of a moth; and in Figure 714 a cross-section of these 

 organs. Each maxilla is furnished with a groove, and the two 

 maxillae are so fastened together that the two grooves form a tube 

 through which the liquid food is sucked. As a rule the maxillae of 

 insects of this order are merely fitted for extracting the nectar from 

 flowers, but sometimes the tips of the maxillae are armed with spines, 

 as shown in Figure 713. This enables the insect to lacerate the tissue 

 of ripe fruits and thus set the juice free, which is then sucked up. 

 Many moths do not eat in the adult state; with these the maxillag 

 are wanting. The two forward-projecting organs between which the 

 maxillae are coiled when present are the labial palpi. In some moths 

 the maxillary palpi are also developed. 



The compound eyes are large and are composed of many small 

 ommatidia. The ocelli, when present, are two in number; they are 

 situated one on each side, above the compound eye and near its mar- 

 gin; the median ocellus is lacking throughout the order; and in the 

 butterflies, the skippers, and some families of moths, all of the 

 ocelli are wanting. 



The antennse are always conspicuous ; they differ greatly in form 

 in different divisions of the order, and, therefore, furnish characters 

 that are much used in the classification of these insects. In some 

 families the basal segment of the antennas is greatly enlarged and forms 

 what has been termed the eye-cap. 



The pro thorax is small, being reduced to a collar between the head 

 and the wing-bearing segments. In many of the more specialized 

 Lepidoptera the pronotum is produced on each side into a flat lobe 

 which in some cases is even constricted at the base so as to become 

 a stalked plate; these lobes are the patagia. 



The legs are long and slender. In some families the front tibiae 

 bear on their inner aspect a mobile pad ; this is termed the epiphysis; 

 in some cases, at least, it is a combing organ used for cleaning the 

 antennae. 



A special feature of the abdomen is the presence in the female 



