Howdy, BugFans,<\/p>\n
The BugLady encountered a deer tick on her scalp last week (second week of March), a reminder that these are very hardy little critters—and—that the uncharacteristically balmy weather is getting lots of stuff going early. So, here\u2019s the deer tick story as told in a BOTW from three years ago along with some hot-off-the-presses additional information and, of course, new pictures.<\/p>\n
The Deer Tick (Ixodes scapularis<\/em>) (not to be confused with the musical group Deer Tick<\/em>) is a critter whose escapades are well known to those of us who live here in God\u2019s Country (at least they should be). It\u2019s notorious for its ability to spread Lyme (not Lymes) disease and because its sesame-seed-size makes \u201ctick checks\u201d a challenge (scroll down to the ruler<\/a>).<\/p>\n Lyme disease is an initially-flu-like disease that doesn\u2019t go away and will escalate if ignored, and it is more treatable early than late. The CDC has a very comprehensive website with information about tests, symptoms, treatment, and prevention at CDC – Lyme Disease<\/a>, (there\u2019s disagreement about Lyme disease testing and treatment, mainly from organizations whose members have spent months and years looking for a clear diagnosis and an effective cure for this frustrating disease). Lyme disease is not \u201ccatching,\u201d and you can\u2019t get it from eating venison from an infected deer (but kneeling on the ground dressing out a deer puts you right down there in DT territory).<\/p>\n When the BugLady moved into her rural home 39 years ago, ticks were scarce, she plucked a wood\/dog tick (Dermacentor variabilis<\/em>) off the dog every 5 years or so, and she never saw a deer tick. In the past four or five years she has seen fewer wood ticks, but deer ticks (a.k.a. Black-legged ticks) have arrived in force and are showing their little heads by late April (chiggers are way more numerous, too). An article in Science Daily<\/em> (June 22, 2011) refers to the \u201csteady march of deer ticks across the Upper Midwest\u201d and reports that the rate of their advance through Indiana and Illinois (having successfully occupied Minnesota and Wisconsin) is two counties per year.<\/p>\n [metaslider id=382]<\/p>\n Non-feeding adult DTs are very small (about 3mm long) and flat and dark (females may look blood-red when they\u2019re empty but not when they\u2019re full), with eight black legs and a black \u201cshield\u201d (called a scutum<\/em>) in back of its head. DTs don\u2019t have any white\/light markings on the scutum, but wood ticks do. A feeding adult female looks like a tiny, over-filled, blue-gray balloon (\u201cas tight as a tick\u201d) (the BugLady is trying to avoid comparisons to grapes here, lest she put BugFans off their feed).<\/p>\n DTs lead a complex, three-stage, two-year life. All three stages are mobile and all three require a blood meal that can take three to five days to complete. Adult DTs are fairly impervious to frosts and can be out and about on winter days that are above freezing. In spring, Mom has a big meal (adult males rarely feed), mates, drops to the ground, and lays thousands of eggs. The first post-egg stage is a minute\u2019 six-legged larva that feeds once during mid-summer on a bird or a small mammal (it\u2019s especially fond of white-footed mice). The well-fed larva leaves its host and overwinters in the leaf litter. The following spring it molts into a poppy seed-sized nymph that feeds again (another mouse, maybe, or a raccoon or squirrel) and then molts into an adult that becomes active in fall. Adults favor large mammals like white-tailed deer.<\/p>\n Ms. DT finds Mr. DT through the magic of aggregation pheromones (chemical perfumes) that cause DTs to gather in groups, allowing boy to meet girl. They may mate on a host, on vegetation, or on the ground. He dies after mating a few times; she dies after laying eggs.<\/p>\n Where does a DT pick up Lyme disease? Typically not from Mom, even if she\u2019s carrying it. An uninfected larva or nymph can pick up the disease from its host; an infected larva can transmit it to its host, and once they\u2019ve picked up the infection, ticks retain it for the rest of their lives. The general estimate is that in high-Lyme areas, 25% of nymphal DTs and 50% of adults carry the bacterium that causes the disease, but according to the American Lyme Foundation, fewer than 5% of DTs south of Maryland are carriers. Dog ticks do not spread Lyme disease (but they are not totally innocent bystanders, either).<\/p>\n DTs are classed as sanguivores<\/em> (animals that ingest fresh blood). They\u2019re opportunistic—to find a host, they\u2019ll often wait at the tips of vegetation in what is called the \u201cquesting position,\u201d sensing the air, waiting for something large to brush against them (top picture<\/a> then scroll down for a Lyme map—we no longer presume that someone who tests positive for Lyme has been \u201cup North\u201d). The biggest mortality factor for ticks may be starvation, and harsh climate can also affect them. <\/p>\n The BugLady originally quoted one source that said \u201cThey typically aren\u2019t eaten by predators because they\u2019re simply too small to see,\u201d but alert BugFan Laura points out that a whole bunch of predators, from shrews and birds to nematodes and soil fungi, have been known to partake (engorged ticks must be a lot easier for larger predators to find). BugFans keep the BugLady honest. <\/p>\n [metaslider id=384]<\/p>\n