Dihammus marianarum (Aurivillius)

Swezey, O. H., 1942, Miscellaneous Families of Guam Coleoptera, Insects of Guam I, Honolulu, Hawaii: Bernice P. Bishop Museum, pp. 150-171 : 169

1. Dihammus marianarum (Aurivillius) .

Monochamus (Haplohammus) Marianarum Aurivillius, Deutsche Ent. Zeitschrift, 216, 1908.

Dihammus Marianarwm (Aurivillius) Coleopt. Catalog. (73): 98, 1922.

Agfayan, March 28, Bryan ; Orote Pen., April 9, Bryan ; Merizo , April 24, Bryan ; Upi Trail , May 5, Usinger; Machanao , June 2, Swezey; Piti , May 2, on Pithecolobium, Usinger ; Dededo , May 11, Usinger; Talofofo , June 11, Usinger; Barrigada , June 12, on Citrus , June 14, on Ficus , June 24, Usinger; Dededo , Sept. 7, reared from Hibiscus tiliaceits, Swezey; Piti , Sept. 22, Oct. 3, Swezey; Yigo , Oct. 18, reared from dead Firns , Swezey; Piti , Nov. 16, at light, Swezey.

This is the largest cerambycid in Guam. It was previously collected by Fullaway in 1911, and determined by Schultze as Dihammus fistulator Germar , a species having a wide range from Malay Peninsula and the Philippines to Australia and Samoa. The specimens identified by Schultze, however, have the lateral shining bare spots of the abdomen, the same as our 1936 specimens, which is a character by which Aurivillius distinguishes marianarum from other closely related species.

The work of the larvae of this beetle is very conspicuous in dead bran(;hes of the breadfruit tree. It also works similarly in Pithecolobium , Ficus , and Hibisrns tiliaceus , and any felled tree. Before getting too old and dried up, the leftover tree tops where logs had been cut were especially likely to have larvae working in them. At Yigo , November 13, larvae were found in living cacao trees . When working in or beneath the inner bark, they had a tendency to go spirally around a branch, which either crippled or killed it. One larva retained for rearing by A. I. Cruz matured February 19, 1937.