THE STYLO PI D,E. 339 



time in the interior, without killing it, emerging after the grub has spun up for the pupa state. It 

 then changes its skin, and comes forth in a shorter and thicker form, in which stage it attaches itself 

 to the upper part of the body of its victim, and feeds by suction, soon afterwards undergoing a second 

 change, and finally devouring the undeveloped Wasp entirely. When full-grown the Hhipiphorus 

 larva closely resembles the grub of a Hymenopterous insect of the family of Fossorial Wasps. 



In the Hornia minutipennis, another parasitic Meloi'd, discovered by Mr. Riley infesting the 

 cells of Mason Bees, the wing-covers in both sexes are reduced to minute scales on the sides of the 

 middle segment of the thorax. This tendency to disappearance in the organs of flight is carried still 

 further in Rhipidius blattarum, a minute European Beetle parasitic on the bodies of living Cock- 

 roaches, the female of which is apterous, and differs little in appearance from its larva, whilst the 

 males have short divergent wing-covers and membranous wings. From this curious little Hetero- 

 meron, which feeds within the bodies of its victims, the transition is not unnatural to the family 

 STYLOPID.E, a group of minute insects, which until recently were believed by all entomologists to 

 constitute a distinct order of insects (STREPSIPTERA), differing from all others in the form of their 

 wings, the parts of their mouth, and the relations between the segments of their thorax. 



The Stylopidse are parasitic on living Bees and Wasps, the females being apterous and larviform, 

 residing permanently in the bodies of the insects they infest, the males winged and active. The 

 latter live but a few hours, and solely for the purpose of aiding in the propagation of the species, 

 seeking the females, whose bodies are embedded, with the exception of a small upper portion, in those 

 of Bees as they fly from flower to flower, and the orifice of whose reproduc- 

 tive organs lies in the exserted part near the head. The males take no 

 nourishment during their short lives, and their mouth-organs are in a 

 rudimentary condition, only the mandibles and one pair of palpi being 

 recognisable. The head is extremely short and broad, the eyes prominent, 

 the antennae curiously forked, and the two anterior segments of the thorax 

 relatively shorter and more closely connected together than in any other STYLOPS SPEXCE: 



group of the Coleopterous order. But the most striking features are the 



greatly expanded membranous wings, coupled with the arrested development of the elytra, which do 

 not serve as wing-covers, but are reduced to the form of slender appendages of thin texture, which 

 in the dried specimens become twisted, and lose all similarity to the corresponding organs in all other 

 Coleoptera. The tarsi are not heteromerous, but consist of two or four joints, and are destitute of 

 claws. Such a combination of characters is not met with in any other group of insects, and lends 

 justification to those entomologists who have treated the Stylopidse as a separate order. There is no 

 part of their structure, however, which can be considered as quite incompatible with the Coleopterous 

 type, except the extremely short prothorax, and the intimate connection of this segment with the 

 middle thorax. 



The early stages and mode of development of the Stylopidse are not essentially different from 

 those of the Meloidae and Caiitharidinse, already described. But the females are viviparous, the eggs 

 hatching within their bodies, and the young crawl forth from an orifice situated in the part of 

 the body of the parent which projects from the abdomen of the Bee. One female gives birth to many 

 thousands of these tiny larvae, which are moderately active hexapocls, and resemble the first stage of 

 the larvse of Sitaris. They crawl forth and attach themselves to the hairs of other Bees, and are by 

 them carried to their cells, where they penetrate the bodies of the Bee-grubs and feed on their 

 substance, undergoing changes not very dissimilar to those of the Meloidse, the larvae in their second 

 stage being footless and blind ; they continue to live in the interior of the Bee without destroying its 

 life, or hindering it in its growth from the larva state to the chrysalis and adult Bee, only in their 

 later stages protruding the anterior part of their bodies between the abdominal segments of the 

 Bee. The female Stylops stops in its development at this stage; the male emerges from its pupa 

 skin in the winged form we have already described. 



Such in brief resume is the life-history of these extraordinary little insects. According to an 

 exhaustive monograph published by Sir Sidney Saunders in 1872, the diversity both of structure and 

 habits among the species composing the group is much greater than was until quite recently supposed. 

 One of them, which inhabits Ceylon, is parasitic on the workers of an Ant, and many species prey 



