Economic Importance of the Parasites of Coccidx. 227 



variety of behaviour prevails among tlie young of different 

 species; but as far as I can judge from the facts which 

 came under my notice and from previous observations, it 

 seems that all the forms are very tenacious of life when 

 young ; I found them wandering for days over the shelves 

 of the hot-house in which I was rearing them. 



Lecaniumhemisphmricum is noted for its unusual powers 

 of locomotion. Signoret * speaking of this Coccid says : 

 " Cette conformation des tarses indiquerait peut-etre que 

 les especes de cette serie sont moins fixes que leurs con- 

 generes." Comstockf confirms this by the statement that 

 " actual observation shows the surmise of Signoret as to the 

 locomotive powers of the insect to have been correct. We 

 have seen the adult insects, when removed from their 

 positions, crawl back with apparent ease." I have seen 

 this happen repeatedly. Reh % made experiments and 

 found that certain young Coccids could move a metre in 

 about an hour. But he thinks, and I agree with him, that 

 it is improbable that their own powers of locomotion are 

 the most important means by which they become distri- 

 buted. The most valuable information on this point is to 

 be found in some briefly-described observations by Hubbard. 

 I cannot do better than quote some passages from this 

 talented and lamented American observer.^ " During the 

 migratory age the restless habit of the young bark-lice 

 impels them to crawl actively about, turning aside for no 

 obstacles, but mounting every object met with in their 

 path. The instinct of self- protection being entirely wanting 

 in these degraded creatures, they make no distinction 

 between dead and living objects, and crawl without hesita- 

 tion upon the bodies of other and larger insects. The 

 latter, impelled by the annoying presence of the intruders, 

 fly away, bearing with them the scale larvae, and thus 

 assist in distributing them upon surrounding plants. . . . 

 But spiders more than any other animals must be con- 

 sidered efficient instruments in this mischievous work. 

 Not only do they transport the lice — and it is an observed 

 fact that the movements of the latter upon their hairy 

 backs do not incommode the spiders — but they also 



* "Essai sur les Coclienilles ou gallinsectes (Homopt^res-Coc- 

 cides)," Ann. Soc. Ent. France (5), iii, 1873, p. 437. 



t ''Keport of the Commissioner of Agriculture for 1880," p. 334. 

 X Jalu-b. Hamb. Wiss. Anhalten, xvii, 1899 ; 3 Beiheft, pp. 1-6. 

 § Amer. Natural, xvi, 1882, p. 411. 



TRANS. ENT. SOC. LOND. 1902. — PART 11. (JUNE) 16 



