THE CANADIAN ENTOMOLOGIST. 23 



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Laverna gleditsc/iicEel/a Chs-in. is much subject to the attacks of hynien- 

 opterous parasites in its larval condition. Yet it is difficult to understand 

 how this is possible under the conditions of its larval life. The first traces 

 of the larva are always found in the pith of the stem or branch of the 

 tree, about an inch from the base of tlie thorn. I have never been able 

 to understand how the larva gets to the pith without leaving some trace 

 of its path from the outside of the stem. The egg must be deposited on 

 the outside of the stem, because the ovipositor of the $ is too soft to be 

 able to penetrate the bark and wood to the pith. It would seem that the 

 eggs of the little chalcid parasites must be deposited on the microscopic 

 larva of the moth as soon as it emerges from the egg, and before it has 

 eaten its way into the branch, because it is impossible to understand how 

 it can be done afterwards, as these little parasites are themselves so small 

 that two of them placed end to end would not extend from the outer sur- 

 face of the bark of the twig to the central pith, and their ovipositors are 

 very short and not exserted. By some means, however, they do manage 

 to reach the larva, and frequently in place of the lepidopterous larva one 

 finds only its shrivelled integument and a dozen or more minute chalcid 

 pupae, looking as if they were plaited together so as to form a chain as 

 long as the larva of the moth. Sometimes, too, one finds the imagines 

 which have not been able to effect their egress, however they may have 

 effected their ingress to the thorn. There are two other species of Chal- 

 cididae sometimes found in a similar predicament, dead in the prison in 

 which they were hatched. One of these in the imago state is about two 

 lines long. I do not know whether these feed on the larva of the Laverna 

 or on one of the other larvae above mentioned. The Laverna larva eats 

 its way to the base of the nearest thorn, usually about an inch distant, 

 then up through its pith a short distance, frequently turning off into the 

 nearest branch. It eats through nearly to the outer surface, leaving only 

 the thin cuticle of the thorn, reaching this point in May, the egg having 

 been deposited on the twig about July or August of the previous year. 

 Here it enters the pupa state, and in ten days or two weeks the imago 

 makes its appearance, the empty pupa skin being left projecting from the 

 little circular hole where it has burst through the cuticle of the thorn. The 

 imago is almost unicolorous, but it ranges from deep glossy brown very 

 faintly bronzed, to a bright bronze or almost golden brown. 



Dr. Schweinfurth mentions (Heart of Africa, v. i. p. g8) and figures 

 the thorns of an African Acacia which have a large swelling at the base 



