{"id":1438,"date":"2015-08-11T15:44:11","date_gmt":"2015-08-11T20:44:11","guid":{"rendered":"https:\/\/uwm.edu\/field-station\/?p=1438"},"modified":"2017-03-28T11:21:25","modified_gmt":"2017-03-28T16:21:25","slug":"arched-hook-tip-moth-family-drepanidae","status":"publish","type":"post","link":"https:\/\/uwm.edu\/field-station\/bug-of-the-week\/arched-hook-tip-moth-family-drepanidae\/","title":{"rendered":"Arched Hook-tip Moth (Family Drepanidae)"},"content":{"rendered":"

Greetings, BugFans,<\/p>\n

Arched Hook-tip Moth<\/h3>\n

This beautiful Arched Hook-tip (Drepana arcuata<\/em>) landed on the house recently, a new species for the porch-light list, and now the BugLady wants to meet its caterpillar<\/a>. She may still have a chance at it—the AHT has two generations (two broods) each summer here in God\u2019s Country, and the second-brood caterpillars should afoot any time now. Pupae<\/a> of the first generation become adults fairly quickly, but pupae of the second generation overwinter and emerge early next summer.<\/p>\n

\"arched-hooktip15-1\"<\/a><\/p>\n

AHTs belong in the \u201cHooktip and False Owlet moth\u201d family Drepanidae (from the Greek word drepana<\/em> meaning sickle), also a newcomer to BOTW. There are about 660 species in the family worldwide (only 8 in the eastern U.S.A.). Drepanid moths are medium-sized moths (wingspread 1\u201d \u2013 1 \u00bd\u201d) that have uniquely-formed hearing organs, and many (but not all) have hooked wing tips. In many species, the proboscis that is short or absent, but the AHT moth does feed. North American members of the family can be found throughout the continent except for the far (far) north—Alaska and the Yukon Territory.<\/p>\n

According to the range map on the mothphotographers<\/em><\/a> website, the AHT is largely missing from the Great Plains and the Gulf Coast but is present across Canada. Based on the pictures on that site and on bugguide.net<\/a>, most adult AHTs are paler than this sable-colored specimen (Borrer calls them \u201cdirty white\u201d). The BugLady read in one source that the members of the summer brood are darker in color.<\/p>\n

Arched Hook-tip Caterpillars<\/h3>\n

AHT caterpillars have their own name—the Masked birch caterpillar<\/a> (their host plants are paper birch and several species of alder). Like other members of their family, AHT caterpillars have reduced\/fused rear legs, so the abdomen tapers dramatically to the rear. Wagner, in Caterpillars of Eastern North America<\/em>, says that they often hold up both head and tail, looking like dragons. Female AHTs lay a half-dozen eggs per leaf, and the caterpillars live and feed communally for the first 10 days or so. They spin silken shelters<\/a> on a leaf surface, often drawing several leaves around them, and they leave their webby homes at night to nibble at the leaf\u2019s edge. Caterpillars will consume several leaves before they pupate, moving from \u201cused\u201d leaves to new ones (they keep the nest cleared of frass<\/em> (bug poop) and they sever the petiole<\/em> (leaf stem) of a fed-upon leaf so as not to signal birds). They never move far from where the eggs were laid, and they pupate in a cocoon hidden within a folded leaf.<\/p>\n

So, what are the AHT\u2019s claims to fame, and why does the BugLady<\/em> want to find a caterpillar?<\/p>\n

First, the moth\u2019s \u201cears.\u201d Lots of insects have hearing organs (tympana<\/em>), which may be located on various parts of an insects\u2019 anatomy. Depending on the family, ears might be found on the thorax or abdomen, or even the wings or mouthparts (in Drepanidae, the ears are located toward the front of the abdomen). The ears of nocturnal moths detect the frequencies of bats, but in some species, they are also receivers for communication between individuals. Ears are popular in the Lepidoptera (even some butterflies, which are diurnal and have no need for bat-detectors, have them, though most butterflies do not produce sound. They are thought to be tuned to the frequency of bird wing-beats). The ears of Drepanid moths are structurally more complicated than those of most other insects, though they\u2019re used to detect the same sounds.<\/p>\n

Second, the caterpillar. Even though they live a sedentary lifestyle within those webbed leaves, AHT caterpillars have developed a number of ways to communicate with perceived threats in their environment. The biggest threat comes from AHT caterpillars that are \u201cin between\u201d nests, and figure that they might evict a nest-owner (building web nests is expensive, energy-wise). Researchers Yack, Smith, and Weatherhead studied AHT caterpillars (a project that was initiated when Jayne Yack, who was rearing some caterpillars in her dining room, heard their vibrations in the quiet room). Here\u2019s what they found:<\/p>\n