STYLOPS 



301 



difference really existing as to the method. When a Stylops 

 carried by an Insect (a Hymenopteron, be it noted, for we have 

 no information whatever as to Hemiptera) produces young, 

 they cover the body of the host as if it were powdered, being 

 excessively minute and their numbers A'ery great ; many hundreds, 

 if not thousands, of young being produced by a single Stylofs. 

 The species of the wasp genus Polistes are specially subject to 

 the attacks of Stylops ; they are social Insects, and a stylopiaed 

 specimen being sickly does not as a rule leave the nest ; in this 

 case the Stylops larva may therefore have but little difficulty in 

 finding its way to a Hymenopterous larva, for even though it 

 may have to live for months before it has the chance of attaching 

 itself to a nest -building female, yet it is clearly in the right 

 neighbourhood. The bee genus Andrena has, however, quite 

 different habits ; normally a single female makes her nest under- 

 ground ; but in the case of a stylopised female it is certain that 

 no nest is built, and no larvae produced by a stylopised example, 

 so that the young triungulins must leave the body of the bee in 

 order to come near their prey. They can be active, and have 

 great powers of leaping, so that it is perhaps in this way possible 

 for them to attach themselves to a healthy female bee. 



We have still only very imperfect knowledge as to the struc- 

 ture and development of Strepsip- 

 tera. Indeed but little informa- 

 tion has been obtained since 

 1843.^ Before that time the 

 mature female was supposed to be 

 a larva, and the triungulins found 

 in it to be parasites. Although 

 the erroneous character of these ^jq, 155. -Portion of early stages of 

 views has been made clear, the ^enos rossii. (After von Sieboid.) 



, , ii i 1 1 A, Small male larva ; B, small female 



problems that have been SUg- larva ; C, full-grown male larva ; D, 



gested present great difficulties. full-grown female larva ; E, the so- 



° '- ° . called ' cephalothorax and adjacent 



Apparently the change from the segment of adult female. (Theuewly- 



triungulin condition (Fig. 154) to '^f j!";^ 1"^™ is very much like that 



& ^ o ^ of stylops shown m Fig. 154.) 



the parasitic larvae (Fig. 1 5 5, A, B) 



is extremely great and abrupt, and it appears also that during 



^ Von Sieboid, Ardi. Katurges. ix. 1843, pp. 137-161. Nassonoffs recent paper 

 is in Russian, but so far as we can gather (of. Zool. CentraUl. i. 1894, p. 766), it does 

 not add greatly to the data'furnished by von Sieboid. 



